A TALE OF TWO QUESTIONS: BENEFITS OF ASKING MORE THAN ONE QUESTION

In the last two months have you had a physical examination?The ability of 660 people to accurately report on their ownrecent health procedures was assessed by comparing the recollectionsof patients to information extracted from their medical records.A major finding was that when people were asked whether theyhad a specific procedure in a given reference period (e.g.,physical exam within the last two months), overreporting occurred.A simple technique reduced overreporting: The technique entailedasking people about the procedure twice, first in connectionwith a different reference period (e.g., physical exam withinthe last six months) and then in connection with the referenceperiod of interest (e.g., physical exam within the last twomonths). Our data support a "Precision" hypothesis: The advantageof the two–time frame questioning procedure is that itconveys to the respondent that the interviewer wants greaterprecision in dating than the single–time frame questionimplies.     

HAVE EFFORTS TO REDUCE SMOKING REALLY CONTRIBUTED TO THE OBESITY EPIDEMIC?

Two of the most notable trends in public health over the past 30 yr are the reductions in smoking rates and the rapid rise in obesity rates. Several studies have investigated the relationship between these trends but have drawn different conclusions. In this article, we revisit this issue, attempting to clarify the prior discrepant results. Overall, we find no support for the claim that rising cigarette taxes have significantly contributed to rising obesity rates. Instead, we find only a moderately sized effect among former smokers . ( JEL I12)     

Performance of Robust GCV and Modified GCV for Spline Smoothing

Abstract. While it is a popular selection criterion for spline smoothing, generalized cross‐validation (GCV) occasionally yields severely undersmoothed estimates. Two extensions of GCV called robust GCV (RGCV) and modified GCV have been proposed as more stable criteria. Each involves a parameter that must be chosen, but the only guidance has come from simulation results. We investigate the performance of the criteria analytically. In most studies, the mean square prediction error is the only loss function considered. Here, we use both the prediction error and a stronger Sobolev norm error, which provides a better measure of the quality of the estimate. A geometric approach is used to analyse the superior small‐sample stability of RGCV compared to GCV. In addition, by deriving the asymptotic inefficiency for both the prediction error and the Sobolev error, we find intervals for the parameters of RGCV and modified GCV for which the criteria have optimal performance.     

PRICE‐DEPENDENT INVENTORY MODELS WITH DISCOUNT OFFERS AT RANDOM TIMES*

We consider an inventory model with a supplier offering discounts to a reseller at random epochs. The offer is accepted when the inventory position is lower than a threshold level. We compare three different pricing policies in which demand is induced by the resellers price variation. Policy 1 is the EOQ policy without discount offers. Policy 2 is a uniform price, stock‐independent policy. Policy 3 is a stock level‐dependent, discriminated price policy. Assuming constant demand rates, expressions are obtained for the optimal order quantities, prices, and profits. The numerical experiments show that if it is better to accept a suppliers discount, then it benefits the reseller to transfer the discount to downstream customers.     

SEQUENCING AND BATCHING FOR TWO CLASSES OF JOBS WITH DEADLINES AND SETUP TIMES

We formulate a general sequencing problem that includes two classes of jobs with setup times, setup costs, holding costs, and deadlines. The formulation is unique in its explicit recognition of the opportunities to exploit productive capacity increases due to batching. An algorithm based on tabu search is then used as a solution method. Computational results are presented that suggest that the algorithm is effective.