A Unifying Framework and Comparison of Algorithms for Non-negative Matrix Factorisation

Non-negative matrix factorisation (NMF) is an increasingly popular unsupervised learning method. However, parameter estimation in the NMF model is a difficult high-dimensional optimisation problem. We consider algorithms of the alternating least squares type. Solutions to the least squares problem fall in two categories. The first category is iterative algorithms, which include algorithms such as the majorise–minimise (MM) algorithm, coordinate descent, gradient descent and the Févotte-Cemgil expectation–maximisation (FC-EM) algorithm. We introduce a new family of iterative updates based on a generalisation of the FC-EM algorithm. The coordinate descent, gradient descent and FC-EM algorithms are special cases of this new EM family of iterative procedures. Curiously, we show that the MM algorithm is never a member of our general EM algorithm. The second category is based on cone projection. We describe and prove a cone projection algorithm tailored to the non-negative least square problem. We compare the algorithms on a test case and on the problem of identifying mutational signatures in human cancer. We generally find that cone projection is an attractive choice. Furthermore, in the cancer application, we find that a mix-and-match strategy performs better than running each algorithm in isolation.     

Organizational environmental orientation and employee environmental in‐role behaviors: A cross‐level study

Amid the growth of scholarly research on environmental workplace behaviors, two limitations stand out. First, there has been scant research on the cross‐level effects of organizational‐level determinants on individual employee environmental behaviors using a methodologically appropriate multilevel analytic approach. Second, there has been an overwhelming focus on voluntary, as opposed to task‐related, employee environmentally friendly behaviors. In addressing these limitations, this field study (N = 615 U.S.‐based employees nested in 51 organizations) makes a theoretical and empirical contribution to the literature, specifically by linking the dimensions of organizational‐level environmental orientation with individual‐level employee environmental in‐role (i.e., task‐related) behaviors using multilevel analysis. The results indicate that organizational internal environmental orientation is positively related to employee recycling behavior. Managerial status exerts a moderating effect, such that the positive relationship between internal environmental orientation and energy‐saving behavior is stronger among managers than among non‐managers. Furthermore, an organization's external environmental orientation has an unequivocal positive relationship only with employee energy‐saving behavior. The theoretical and practical implications of the findings are discussed.     

Optimal delegation choices in the presence of an incongruent performance measure and double moral hazard

An owner‐manager can delegate two tasks to an agent. A time constraint prevents him from completing both tasks at first‐best levels. He can (a) perform both tasks personally to the extent possible, (b) delegate one task to an agent, or (c) delegate both tasks. Agency costs arise from a congruity problem, a double moral hazard problem, and a risk and incentive trade‐off. Delegation becomes more favorable the stronger the time constraint. Once delegation is preferred, the optimal extent of delegation depends on the relation of sensitivity to productivity ratios in both tasks. Agency costs not necessarily increase in delegation level.     

Framing Effects in Stock Market Forecasts: The Difference Between Asking for Prices and Asking for Returns

Studies analyzing return expectations of financial market participantslike fund managers, CFOs or individual investors are highlyinfluential in academia and practice. We argue and show thatthe results in these surveys above are easily influenced bythe elicitation mode of return expectations. Surveys that askfor future stock price levels are more likely to produce meanreverting expectations than surveys that directly ask for futurereturns. Furthermore, we conduct a questionnaire study thatexplicitly analyzes whether the specific elicitation mode affectsreturn expectations in the above direction. In our study, subjectswere asked to state mean forecasts for seven time series. Usinga between subject design, one half of the subjects was askedto state future price levels, the other group was directly askedfor returns. We observe a highly significant framing effect.For upward sloping time series, the return forecasts statedby investors in the return forecast mode are significantly higherthan those derived for investors in the price forecast mode.For downward sloping time series, the return forecasts givenby investors in the return forecast mode are significantly lowerthan those derived for investors in the price forecast mode.We argue that this finding is consistent with behavioral theoriesof investor expectation formation based on the representativenessheuristic.     

The Technical Efficiency Impact of Farm Credit Programmes: A Case Study of Northern Germany

We analyse the technical efficiency of dairy farms in Schleswig‐Holstein that took part in the European Farm Credit Programme over the period 1987 to 1994. One goal of this programme is to increase the productivity of farms. We test whether participants show higher technical efficiency. We utilise a stochastic frontier model that allows for heteroscedasticity and estimation of determinants of technical inefficiency. Statistical tests indicate dominance of this model over alternative specifications. On average, we observe a high level of technical efficiency between 1987–94, but participation in the programme has rather led to a slight decrease. Thus, the programme seems to have failed to increase the competitiveness of farms.     

China and India in the global economy

The purpose of this overview paper is to present the economic growth in China and India over the last three decades with a specific focus on the integration of these countries into the global economy. In the first part, we briefly review the long-run process of growth and institutional change, emphasizing the reforms leading to the “opening” of the two economies. Then, we focus on key structural features and compare the recent development processes of the two countries. At the end, there are some hints about certain persisting imbalances and the sustainability of the growth processes.