Use of the principal component method in the maximum likelihood estimation procedure of the logit model

The maximum likelihood estimates of a qualitative response market are solved by an iterative procedure. When severe multicollinearity exists among the explanatory variables, this procedure may fail to converge. In this note, using a bank-failure model, we demonstrate how the principle component method can make the iterative procedure converge when it fails to do so in the untransformed model.     

An analysis of some short-term health effects of air pollution in the Washington,D.C. metropolitan area

This study assesses some of the short-term health effects of air pollution in Washington, D.C. Specifically, regression models are formulated to explain health-care visits to a group practice medical care plan. Primary interest is focused on the effects of mobile-source air pollutants, particularly photo-chemical oxidants. Meteorological conditions, as well as other variables thought to influence the consumption of medical services, are included in the models as explanatory variables. The study found only a small effect of air pollution levels on the health-care visits to the group practice.     

Asset returns and inflation

We estimate the extent to which various assets were hedges against the expected and unexpected components of the inflation rate during the 1953–1971 period. We find that U.S. government bonds and bills were a complete hedge against expected inflation, and private residential real estate was a complete hedge against both expected and unexpected inflation. Labor income showed little short-term relationship with either expected or unexpected inflation. The most anomalous result is that common stock returns were negatively related to the expected component of the inflation rate, and probably also to the unexpected component.     

The information in the term structure

This paper presents a regression approach to measuring the information in forward interest rates about time varying premiums and future spot interest rates. Like earlier work, the regressions identify variation in the expected premiums on longer-maturity Treasury bills. The more novel evidence concerns the forecasts of future spot rates in forward rates. The regressions provide evidence that the one-month forward rate has power to predict the spot rate one month ahead. During periods preceding 1974, forward rates have reliable forecast power for one-month spot rates up to five months in the future.     

A Recommended formula for scoring probabilistic multiple-choice tests

This paper addresses the issue of how best to score test responses obtained when using Probabilistically Answered Examinations (PAE). After discussing the PAE methodology, the paper identifies and explores the attributes of a simple, intuitively appealing scoring rule. The results of this analysis suggest that, in many classroom situations, this simple scoring rule produces indices of test effectiveness that are at least as good as those produced by more complicated and costly scoring rules. These tentative findings are drawn upon in support of the use of this simple scoring rule with PAE.     

Security design,market risk and round quotes in the treasury bond market

Prior literature finds that the tendency of price-endings to cluster on rounder fractions increases with price volatility. We estimate the separate influences and relative importance of the determinants of price volatility, security design and market risks. Our data is from a market setting that is ideal for isolating and studying the relations of interest. Results for both quote and trade prices indicate that the tendency to use round price-endings increases with both a security’s inherent risk, attributable to security design, and variation over time in market risks. Security design influences clustering more than market risks, but market risks are influential in determining clustering once security design is fixed. The estimated effects are strongest in the on-the-run market segment where liquidity facilitates the aggregation of information into price.     

Brentuximab vedotin in relapsed/refractory Hodgkin lymphoma post-autologous stem cell transplant: a cost-effectiveness analysis in Scotland

Objective: To evaluate cost-effectiveness of brentuximab vedotin in patients with relapsed/refractory Hodgkin lymphoma who have received autologous stem cell transplantation, from a Scottish healthcare payer perspective.

Methods: A Microsoft Excel-based partitioned survival model comprising three health states (progression-free survival [PFS], post-progression survival, and death) was developed. Relevant comparators were chemotherapy with or without radiotherapy (C/R) and C/R with intent to allogeneic hematopoietic stem cell transplantation (alloSCT). Data were obtained from the pivotal phase II single-arm trial in 102 patients (SG035-0003; NCT00848926), a systematic literature review and clinical expert opinions (where empirical evidence was unavailable). PFS and overall survival for brentuximab vedotin were estimated using 5-year follow-up data from SG035-0003, and extrapolated using event rates observed for comparator treatments from published survival data. Resource use included drug acquisition and administration; alloSCT; treatment of adverse events; and long-term follow-up. Deterministic and probabilistic sensitivity analyses were conducted to evaluate the impact of uncertainty.

Results: In the base case, the incremental cost-effectiveness ratio (ICER) for brentuximab vedotin was £38,769 per quality-adjusted life year (QALY) vs C/R, whereas C/R with intent to alloSCT was dominated by brentuximab vedotin. ICERs for brentuximab vedotin generated by the deterministic sensitivity analysis ranged between £32,000–£54,000 per QALY. Including productivity benefits reduced the ICER to £28,881 per QALY.

Limitations: Limitations include lack of comparative data from this single arm study and the heterogeneous population. Inconsistent baseline characteristic reporting across studies prevented complete assessment of heterogeneity and the extent of potential bias in clinical and cost-effectiveness estimates.

Conclusions: Although the base case ICER is above the threshold usually applied in Scotland, it is relatively low compared with other orphan drugs, and lower than the ICER generated using a previous data cut of SG035-0003 that informed a positive recommendation from the Scottish Medicines Consortium, under its decision-making framework for assessment of ultra-orphan medicines.     

Consumers' Attitudes Towards Intermission Time Utilization In Movie Theatres

This article discusses the issue of cinema screen commercials and suggests that it should be considered within the context of movie theatre intermission time utilization, where the other alternatives are short, commercially sponsored films or illuminated theatres. A two-stage attitudinal survey of movie goers shows that the majority prefer to have something on the screen during intermission time. Respondents expressed negative attitudes towards cinema screen commercials, resulting in short, commercially sponsored films being the most preferred alternative. Negative attitudes do not imply agreement with the banning of commercials, nor a willingness to share its costs. The relative ranking of illuminated theatres over cinema screen commercials changed after respondents were exposed to the economic implications of their choice.