New Product Portfolio Management Decisions: Antecedents and Consequences

This research employs organizational information processing theory to propose and examine the antecedents and consequences of new product portfolio management (NPPM) decisions. Understanding NPPM decisions is an important research area because these decisions affect firm profitability but are difficult to make because of limited reliable information. Recent survey results of Product Development and Management Association members and other NPPM professionals suggest nearly half of initial new product ideas are chosen to advance through the new product development (NPD) pipeline via informal processes. Thus, managers wield considerable influence in NPPM. Yet only limited research quantitatively examines how NPPM decisions impact performance and the role of manager dispositions. Using as the research context a marketing simulation exercise conducted with mid‐level managers, this research reveals important insights into the impact of the three NPPM dimensions—value maximization, balance, and strategic fit—on NPD and firm performance. The analysis suggests a critical role for the NPPM dimension of balance as it is the single dimension impacting performance. However, value maximization is relevant as a criterion for competing because, overall, managers see this dimension as important. At the same time, managers are cautioned in their use of strategic fit as it appears this dimension may constrain innovative choices. Furthermore, three manager dispositions proposed from organizational information processing theory—directive leadership style, need for cognition, and risk perceptions—all influence NPPM dimensions. Managers are recommended to consider the personality traits of managers involved in NPPM decisions to ensure thorough consideration of all dimensions.     

Assessing New Product Development Practices and Performance: Establishing Crucial Norms

In 1968 and 1982 cross-sectional studies of the conduct and performance of new product development were reported, the wide-ranging results of which have been widely reproduced and cited as norms for product development. Since the more recent study, many changes in the practice and environment of product development have occurred. Albert Page describes the findings of a new cross-sectional study, sponsored by PDMA, which reports on the current status of new product development and updates those commonly referred to norms. On the one hand, this article reports that the state of practice, covering both structure and process, has improved, although there is still substantial room for further improvement. On the other hand, the results for five different measures of firm and program performance indicate these practice improvements have not resulted in notable improvements in the overall performance of the new product development activity within the responding companies.     

New Product Development: Impact of Project Characteristics and Development Practices on Performance

Concurrent product development process and integrated product development teams have emerged as the two dominant new product development (NPD) “best practices” in the literature. Yet empirical evidence of their impact on product development success remains inconclusive. This paper draws upon organizational information processing theory (OIPT) to explore how these two dominant NPD best practices and two key aspects of NPD project characteristics (i.e., project uncertainty and project complexity) directly and jointly affect the NPD performance. Contrary to the “best practice” literature, the analysis, based on 266 NPD projects from three industries (i.e., automotive, electronics, and machinery) across nine countries (i.e., Austria, Finland, Germany, Italy, Japan, Korea, Spain, Sweden, and the United States), found no evidence of any direct impact of process concurrency or team integration on overall NPD performance. Instead, there is evidence of negative impact of the interaction between project uncertainty and concurrent NPD process and positive impact of the interaction between project complexity and team integration on overall NPD performance. Moreover, the study found no evidence of any direct negative impact of project uncertainty or complexity on overall NPD performance as suggested in the literature, but found evidence of a direct positive relationship between project complexity and overall NPD performance. The practical implications of these results are significant. First, neither process concurrency nor team integration should be embraced universally as best practice. Second, process concurrency should be avoided in projects with high uncertainty (i.e., when working with unfamiliar product, market, or technology). Finally, team integration should be encouraged for complex product development projects. For a simple product a loosely integrated team or a more centralized decision process may work well. However, as project complexity increases, team integration becomes essential for improved product development. There is no one‐size‐fits‐all solution for managing NPD projects. The choice of a product development practice should be determined by the project characteristics.     

New Product Management Practices of Small High Technology Firms

Various methods exist for managing the planning, cost estimating, scheduling and statusing of new product development projects. David Boag and Brenda Rinholm investigate whether the use of formal management procedures and structured frameworks are the most effective methods for achieving control over new product development activities. This article describes the new product development management practices of 33 small and medium-sized high technology companies. The authors employ a judgmental procedure to group the firms into three stages of development for their management of new products. Findings indicate that success at new product development is greater for more formalized companies than for companies which are less formalized or which use informal methods.     

Exploring Retail Bank Performance and New Product Development: A Profile of Industry Practices

Based on their survey, Eric Reidenbach and Donald Moak report that various aspects of new product development practices are associated with different levels of retail bank performance. Such practices and activities as the existence of a formal evaluation process, the existence of new product managers, the length of time a product spends in development, and the percentage of the operating budget spent on new product development tend to vary according to bank performance. Top performers have decidedly different new product development processes, structures, and practices than do average or negative performers.     

PDMA Research on New Product Development Practices: Updating Trends and Benchmarking Best Practices

Product development professionals may have the feeling that yet another buzzword or magic bullet always lurks just around the corner. However, researchers have devoted considerable effort to helping practioners determine which tools, techniques, and methods really do offer a competitive edge. Starting 30 years ago, research efforts have aimed at understanding NPD practices and identifying those which are deemed “best practices.” During the past five years, pursuit of this goal has produced numerous privately available reports and two research efforts sponsored by the PDMA. Abbie Griffin summarizes the results of research efforts undertaken during the past five years and presents findings from the most recent PDMA survey on NPD best practices. This survey, conducted slightly more than five years after PDMA's first best-practices survey, updates trends in processes, organizations, and outcomes for NPD in the U.S., and determines which practices are more commonly associated with firms that are more successsful in developing new products. The survey has the following objectives: determining the current status of NPD practices and performance; understanding how product development has changed from five years ago; determining whether NPD practice and performance differ across industry segments; and, investigating process and product development tools that differentiate product development success. The survey findings indicate that NPD processes continue to evolve and become more sophisticated. NPD changes continually on multiple fronts, and firms that fail to keep their NPD practices up to date will suffer an increasingly marked competitive disadvantage. Interestingly, although more than half of the respondents use a cross-functional stage-gate process for NPD, more than one-third of all firms in the study still use no formal process for managing NPD. The findings suggest that firms are not adequately handling the issue of team-based rewards. Project-completion dinners are for the most frequently used NPD reward; they are also the only reward used more by best-practice firms than by the rest of the respondents. The best-practice firms participating in the study do not use financial rewards for NPD. Compared to the other firms in the study, best-practice firms use more multifunctional teams, are more likely to measure NPD processes and outcomes, and expect more from their NPD programs.     

Best Practices for New Product Pricing: Impact on Market Performance and Price Level under Different Conditions

To date, research on new product pricing has predominantly been approached as a choice between market skimming and penetration pricing. Despite calls for research that addresses other complexities in new product pricing, empirical research responding to these calls remains scarce. This paper examines three managerial price‐setting practices for new products, i.e., value‐informed, competition‐informed, and cost‐informed pricing. By engaging in these practices, managers can develop and compare quantifications in order to attain an introduction price for the product. The authors draw on consumer price perception literature, Monroe's pricing discretion model, and numerical cognition literature to develop hypotheses about the impact of price‐setting practices on new product market performance and price level. By studying the effects on market performance and price level, the paper provides insights that may help explain the growth of new products and address the problems of underpricing. The hypotheses are tested in a management survey of 144 production and service companies. The results indicate which pricing practices are superior for the achievement of either higher market performance or higher prices in specific product and market conditions. Whereas value‐informed pricing has an unambiguous positive impact on relative price level and market performance, the results also suggest that in many cases engaging in value‐informed pricing is not enough. The effects of cost‐informed and competition‐informed pricing may differ depending upon the objective (market performance or higher prices), product conditions (product advantage and relative product costs), and market condition (competitive intensity). Engaging in inappropriate pricing practices leads to a decline in new product performance. Moreover, bad pricing practices make the positive effect of product advantage on the outcome variables disappear. The latter finding suggests that companies can jeopardize their efforts and investments in the new product development process if they engage in the wrong price‐setting practices. The findings imply that managers should consider different factors in new product pricing. First, when launching a new product, they should determine their explicit pricing objective, either stressing market performance or a higher price level. To determine the most appropriate pricing practices, however, they should next assess their situation in terms of product advantage, relative product costs, and competitive intensity. Together with the pricing objective, these conditions determine the best pricing practice. On a higher level, the findings imply that companies should invest in knowledge development in order to engage in the appropriate pricing practices for each product launch.     

Measuring New Product Portfolio Innovativeness: How Differences in Scale Width and Evaluator Perspectives Affect its Relationship with Performance

Portfolio innovativeness is a central variable in innovation management. However, the impact of portfolio innovativeness on new product development (NPD) performance is unclear, which may partly be due to the construct's multifaceted nature. Different facets may reflect different degrees of innovativeness and may have different relationships with performance. In addition, firm members with different functional backgrounds may perceive and thus assess these facets differently, which again may influence the performance effect of portfolio innovativeness. Based on a sample of 746 CEOs and marketing as well as technology professionals from 117 firms and using Item Response Theory (IRT), a multifaceted scale of portfolio innovativeness, whose facets are able to cover the entire innovativeness spectrum, is developed. In addition, it is shown that the performance impact of portfolio innovativeness is dependent on the facets included in the scale, and on the specialization of the professional assessing the facets. Inverted U‐shaped performance effects are found when the scale covers the entire spectrum of innovativeness, and linear positive or zero effects with different types of more narrowly modeled scales. Inverted U‐shaped performance effects are also found when technology professionals assess the facets, while the assessments by marketing professionals lead to linear positive effects.     

The Impact of Product Portfolio Strategy on Financial Performance: The Roles of Product Development and Market Entry Decisions

Innovation is one of the most important issues facing business today. The major difficulty in managing innovation is that managers must do so against a constantly shifting backdrop as technologies, competitors, and markets constantly evolve. Managers determine the product portfolio through key decisions about product development and market entry. Key strategic questions are what portfolio strategies provide the greatest reward. The purpose of this study is to understand the relative financial values of each component of a product portfolio. Specifically, the paper examines the short‐term and long‐term financial impacts of product development strategy and market entry strategy. These strategies reflect two critical tensions that must be balanced in product portfolio decision making and essentially determine a firm's product portfolio. In doing so, the paper also investigates how a firm's capabilities drive each component of a product portfolio. From the empirical analyses in the context of the biomedical device industry, the paper found important insights regarding product portfolio strategies. First, a large product portfolio helps a firm's financial performance. In particular, the pioneering new products have strongest impacts on short‐term performances, and nonpioneering mature products do not provide significant contribution. Second, the results indicate a persistent first‐mover advantage. The first‐to‐market new products yield not only an immediate effect, but also persistent long‐term effects, suggesting that it is important to be first in the market even though there may be short‐term losses. Third, the results suggest the need to balance between “mature” and “new” products. Also, firms need to balance “first‐to‐market” and “late‐entered” products. Because a new or pioneering product requires more resource, it may hurt other products in the portfolio. Thus, without support from mature or follower products, new products and pioneering products alone may not increase firm sales or profit. Fourth, from a long‐term perspective, the paper found that the financial market only rewards a firm's overall capability to deliver new products first in the marketplace. Thus, short‐term performance is mainly driven by product‐level innovativeness, whereas firm‐level innovativeness enhances forward‐looking long‐term performance. Fifth, the paper also found that pioneering new products are driven by integrating both primary and complementary technological capabilities. And nonpioneering new products are mainly driven by the capabilities in primary technology domain. These results provide important insight into the relative value and timing of return on investment in radical versus incremental innovation and alternative market entry strategies. By understanding the performance trade‐offs of these different factors in the short and long term, one can develop better guidelines for optimizing innovation strategies, and their dependence on both external and internal environmental conditions.     

Management Practices Influencing New Product Success and Failure in the United States and Scandinavia: A Cross-Cultural Comparative Study

This comparative cross-cultural study of United States (U.S.) and Scandinavian telecommunications products found both similarities and differences in the successful new product development (NPD) management practices within the U.S. and Scandinavia. Proficiencies in conducting development, marketing, and customer service activities were identified as important to NPD success in both Scandinavia and the U.S. However, differences between the U.S. and Scandinavia were found with regard to the importance of research and development/marketing integration and project manager competency, with these aspects being more important to NPD success in the U.S. Additional differences between Scandinavia and the U.S. were found in the successful NPD strategies for entering familiar versus unfamiliar markets, with the Scandinavian systems being more oriented toward product design strategies. The overall results characterized U.S. NPD management systems as product-market oriented, task focused, and project management driven. By comparison, the Scandinavian NPD management systems were characterized as product-service oriented, driven by enduring interpersonal relationships and socially oriented to helping others. These characterizations were found to be consistent with dissimilarities in the national cultures of the U.S. and Scandinavia, suggesting that some core NPD management principles may be generally important to success, whereas others may be culturally dependent. The importance of recognizing these differences is pointed out in a discussion of their implications for NPD theory and practice in today's global economy. © 1999 Elsevier Science Inc.     

Exploring New Product Development Project Review Practices*

Most organizations use new product development (NPD) processes that consist of activities and review points. Activities basically solve problems and gather and produce information about the viability of successfully completing the project. Interspersed between the development activities are review points where project information is reviewed and a decision is made to either go on to the next stage of the process, stop it prior to completion, or hold it until more information is gathered and a better decision can be made. The review points are for controlling risk, prioritizing projects, and allocating resources, and the review team typically is cross‐disciplinary, comprising senior managers from marketing, finance, research and development (R&D), or manufacturing. Over the past four decades, research has greatly advanced knowledge with respect to NPD activities; however, much less is known about review practices. For this reason, the present paper reports findings of a study on NPD project review practices from 425 Product Development & Management Association (PDMA) members. The focus is on three decision points in the NPD process common across organizations (i.e., initial screen, prior to development and testing, and prior to commercialization). In this paper, the number of (1) review points used, (2) review criteria, (3) decision makers on review committees and the proficiency with which various evaluation criteria are used are compared across incremental and radical projects and across functional areas (i.e., marketing, technical, financial). Furthermore, the associations between these NPD review practices and new product performance are examined. Selected results show that more review points are used for radical NPD projects than incremental ones, and this is related to a relatively lower rate of survival for radical projects. The findings also show that the number of criteria used to evaluate NPD projects increases as NPD projects progress and that the number of review team members grows over the stages, too. Surprisingly, the results reveal that more criteria are used to evaluate incremental NPD projects than radical ones. As expected, managers appear to more proficiently use evaluation criteria when making project continuation/termination decisions for incremental projects; they use these criteria less proficiently during the development of radical projects, precisely when proficiency is most critical. At each review point, technical criteria were found to be the most frequently used type for incremental projects, and financial criteria were the most commonly used type for radical ones. Importantly, only review proficiency is significantly associated with performance; the number of review points, review team size, and number of review criteria are not associated with new product performance. Furthermore, only the coefficient for proficiently using marketing criteria was significantly related to new product program performance; the proficiency of using financial and technical information has no association with performance. Finally, across the three focal review points of the NPD process in this study, only the coefficient for proficiency at the first review point, (i.e., the initial screen) is significantly greater than zero. The results are discussed with respect to research and managerial practice, and future research directions are offered.     

New Product Development Practices of Industrial Marketers*

William L. Moore personally interviewed a number of senior managers employed in 25 large industrial marketing companies about new product development practices. These managers are familiar with all phases of the development of typical new products, from the time ideas are generated until market introduction. Most respondents were either division heads or those directly responsible for a division's new product development program. In agreement with a previous study, the use of formal new product strategies and sophisticated quantitative marketing research techniques was found to be lacking in most companies. However, many other elements of the new product development process were carried out more completely than previously reported. For example, respondents reflected sensitivity to informal understanding of new product strategies. A number of the less sophisticated, small scale qualitative research methods actually used may be more appropriate than more sophisticated methods. While several research areas are suggested, the general assessment of the new product practices of these firms is more positive than that of Feldman and Page.     

New Product Development Performance and the Interaction of Cross-Functional Integration and Knowledge Management

Previous research on cross-functional integration between research and development (R&D) and marketing has focused on the development of appropriate structural modes and levels of integration and cooperation across the R&D–marketing interface. A gap in the previous research in this area has been the failure to investigate the integration of information from past related product development projects (i.e., knowledge management). In this investigation of R&D–marketing integration, variables from the emerging research literature on organizational learning and knowledge management are examined. By simultaneously investigating the effects of knowledge management variables and R&D–marketing integration, this gap in the literature is addressed. The results demonstrate that the combined effects of R&D–marketing integration and knowledge management in the form of recording, retrieving, and reviewing information from past projects results in interaction effects. In 8 of 18 tests interactions were found. In 6 of 18 tests these resulted in the form of amplification effects with dependent variables such as product prototype development proficiency, product launch proficiency, technological core competency fit, and design change frequency.     

Speed-to-Market and New Product Performance Trade-offs

When pressed to accelerate a development effort, more than a few managers have responded in terms such as “Good, fast, cheap … Pick any two.” Time-to-market decisions clearly play an important role in determining the ultimate success or failure of a new product. Just as clearly, however, speed to market is not the sole determinant of success. The seemingly offhanded “Pick any two” response points to the tradeoffs that product development managers must make in their decisions about development time and costs. Barry Bayus discusses the relationship between product development time and costs, and he fomulates a mathematical model that simultaneously considers the decisions regarding time-to-market and product performance levels. He applies the model to two competitive scenarios, and he identifies the optimal entry timing and product performance decisions for various market, demand, and cost conditions. In the first scenario, a firm must decide whether to accelerate development efforts to catch a competitor that has just introduced a new product. Analysis of the tradeoffs among the various parameters in the model suggests that fast development of low-performance products is optimal under the following conditions: a relatively short window of market opportunity, a weak competitor, and relatively high development costs. For example, if the competitor is weak, high performance levels are not necessary and the firm can safely reduce time-to-market. Under the same scenario (that is, accelerating development to catch a competitor), the analysis suggests that fast development of products with high performance levels is optimal under conditions of relatively high sales and relatively flat development costs. In the second scenario, the firm must decide whether to speed development efforts to beat the competition to market. Analysis of the various tradeoffs for this scenario suggests that first-to-market status for a product with a high performnace level is optimal under the following conditions: a relatively long window of market opportunity, relatively high sales, and relatively flat development costs. With a long product lifecycle, stable margins, and high sales, the firm can generate sufficient revenue to offset the increased cost incurred in speeding a high-performance product to market. Beating a competitor to market with a low-performance product is never optimal for the cases considered here.     

Industrial New Product Launch Strategies and Product Development Performance

Just as reporters must answer a few fundamental questions in every story they write, decision-makers in the new product development (NPD) process must address five key issues: what to launch, where to launch, when to launch, why to launch, and how to launch. These decisions involve significant commitments of time, money, and resources. They also go a long way toward determining the success or failure of any new product. Deeper insight into the tradeoffs these decisions involve may help to increase the likelihood of success for product launch efforts. Erik Jan Hultink, Abbie Griffin, Susan Hart, and Henry Robben present the results of a study that examines the interplay between these product launch decisions and NPD performance. Noting that previous launch studies focus primarily on the tactical decisions (that is, how to launch) rather than on the strategic decisions (what, where, when, and why to launch), they explore not only which decisions are important to success, but also the associations between the two sets of decisions. Because the strategic launch decisions made early in the NPD process affect the tactical decisions made later in the process, their study emphasizes the importance of launch consistency—that is, the alignment of the strategic and tactical decisions made throughout the process. The survey respondents—managers from marketing, product development, or general management in U.K. firms—provided information about 221 industrial new products launched during the previous five years. The responses identify associations between various sets of strategic and tactical decisions. That is, the responses suggest that the strategic decisions managers make regarding product innovativeness, market targeting, the number of competitors, and whether the product is marketing- or technology-driven are associated with subsequent tactical decisions regarding branding, distribution expenditure and intensity, and pricing. The study also suggests that different sets of launch decisions have differing effects on performance of industrial new products. In this study, the greatest success was enjoyed by a small group of respondents categorized as Niche Innovators. Their launch strategy involves a niche focus, targeting innovative products into markets with few competitors. Tactical decisions made by this group include exclusive distribution, a skimming pricing strategy, and a broad product assortment.     

Determinants of New Product Performance: A Review and Meta-Analysis

Previous empirical research on new product performance has provided considerable evidence that a wide variety of antecedent factors can influence the outcomes of new product development activity. Mitzi Montoya-Weiss and Roger Calantone conducted a comprehensive review of this literature and observed a wide variety of study designs and methodological approaches. They developed quantitative comparisons of the results, which, although cumbersome, provide a look at the persistent exploratory nature of this research. They report a wide variation in results that are surprisingly nonconvergent. Recommendations for broadening the range of factors considered and other approaches for accelerating the forward movement of the discipline are provided.     

The Breakfast of Champions: Associations Between Champions and Product Development Environments, Practices and Performance

According to conventional wisdom, if an innovative new product development (NPD) effort is to stand any chance for success, the project must have a champion. The role of the champion has taken on almost mythic proportions, through oft-told tales of the development of such disparate products as instant cameras, automobiles, and microprocessors. Notwithstanding the purportedly essential role that champions play, however, we have only anecdotal evidence of the manner in which effective champions operate and the benefits that they offer. Stephen K. Markham and Abbie Griffin suggest that before we can explore questions about how champions affect product development performance, we must address an even more fundamental issue: whether champions actually influence performance. Using data from the 1995 PDMA study of best practices in product development, they test various widely held assumptions about champions and NDP performance. Specifically, they investigate the association between championing and the following variables: NPD performance at the program, firm, and project levels; industry characteristics; and project- and firm-related NPD characteristics. In several respects, the results of their study run counter to current beliefs about product development champions. For example, the study suggests that champions are just as likely to be found in large firms as they are in small firms. Similarly, the results indicate that the likelihood of finding a champion does not differ significantly between technology-driven firms and marketing-driven firms. For the firms in this study, champions are no more likely to support radical innovations than they are to back incremental innovations or product line extensions. The results of the study suggest that champions do not directly affect firm-level NPD performance. Instead, the results of this study associate increased championing with higher levels of NPD program performance, which positively affects firm-level performance. The results of this study also do not support the notion that a champion can directly improve the market success of a particular project.     

Strategic Alignment and New Product Development: Drivers and Performance Effects

Strategic alignment is widely accepted as a prerequisite for a firm's success, but insight into the role of alignment in, and its impact on, the new product development (NPD) process and its performance is less well developed. Most publications on this topic either focus on one form of alignment or on one or a limited set of NPD performance indicators. Furthermore, different and occasionally contradictory findings have been reported. NPD scholars have long argued for the importance of fit between context and NPD activities. However, this body of literature suffers from the same weakness: most publications have a limited scope and the findings are not always consistent with results reported previously. This study addresses these deficiencies by examining (1) the effects of various internal and external factors on different forms of alignment, and (2) the effects of these forms of alignment on a set of NPD performance indicators. Strategic planning and innovativeness appear to affect technological, market, and NPD‐marketing alignment positively. Environmental munificence is negatively associated with NPD‐marketing alignment, but has no effect on the two other forms of alignment. Technological change has a positive effect on technological alignment, a negative effect on NPD‐marketing alignment, but no effect on market alignment. These findings suggest that internal capabilities are more likely to be associated with the development of strategic alignment than environmental factors are. Furthermore, technological and NPD‐marketing alignment affect NPD performance positively, while market alignment does not have any significant performance effects.     

Principles of New Product Management: Exploring the Beliefs of Product Practitioners

Conventional wisdom might lead us to conclude that the various disciplines involved in product development and management are often at cross-purposes. For example, practitioners from R&D and engineering have been known to suggest that marketing fails to understand the technical trade-offs involved in product management decisions. Conversely, marketing professionals sometimes complain that their technology-oriented colleagues pursue product development initiatives without adequate market awareness. And practitioners from both sides of this debate have asserted that research on new product development tends to be of the ivory tower variety, with little or no relevance for industry. Are such complaints valid? Perhaps it is time for a reality check. By searching academic literature on product development, Roger J. Calantone, C. Anthony Di Benedetto, and Ted Haggblom have compiled a list of 40 fundamental principles of new product development. This list forms the basis for a survey of new product practitioners from marketing and technical disciplines. The study provides a means for assessing whether practitioners agree with the fundamental principles of new product development that are identified in current academic literature. By obtaining responses from both marketing and technical professionals, the survey also sheds light on whether those two groups hold fundamentally different beliefs regarding new product development. The survey results reveal strong overall agreement among practitioners regarding these fundamental principles of new product management. Managers believe that 80% of the principles are either usually or almost always true. In other words, the survey results support the idea that the academic community is pursuing research issues that are relevant to practitioners, and that they are reaching valid conclusions. There are only a few cases in which the responses from the technical and marketing practitioners differ. Those disagreements probably result from differences in the basic orientations of the two groups. For example, it is not surprising that marketing managers would be more likely to agree that “product users and the marketplace form the most important source for new product ideas,” while technical managers more strongly support the idea that “radically new technologies constitute an important source of new product ideas.” The respondents noted overall disagreement with only a few of the 40 principles. In many of these cases, the academic literature has reached mixed conclusions. In other words, these “principles” might actually be oversimplifications, and further research is probably needed before we can fully understand the issues involved.