A non-normal class of distribution function for dose-binary response curve*

A non-normal class of distribution (Edgeworth Series distribution) function in three and four parameters has been considered for dose-binary response relationship. This class accounts for the non-normality (expressed in terms of skewness and kurtosis) present in the relationship in addition to the usual location and scale parameters (generally considered by two parameter models). We present the maximum likelihood method of estimation of the parameters and test of probit (normal distribution) hypothesis. Edgeworth Series distribution when fitted to the data of Milicer & Szczotka (1966) showed an excellent closeness to the observed values, significant improvement over probit and logit fit (Aranda-Ordaz, 1981), and better fit compared to Prentice (1976) model.     

Testing order restricted hypotheses with proportional hazards

Inferences for survival curves based on right censored continuous or grouped data are studied. Testing homogeneity with an ordered restricted alternative and testing the order restriction as the null hypothesis are considered. Under a proportional hazards model, the ordering on the survival curves corresponds to an ordering on the regression coefficients. Approximate likelihood methods are obtained by applying order restricted procedures to the estimates of the regression coefficients. Ordered analogues to the log rank test which are based on the score statistics are considered also. Chi-bar-squared distributions, which have been studied extensively, are shown to provide reasonable approximations to the null distributions of these tests statistics. Using Monte Carlo techniques, the powers of these two types of tests are compared with those that are available in the literature.     

REGRESSION ANALYSIS USING SCRAMBLED RESPONSES

This paper investigates the general linear regression model Y = Xβ+e assuming the dependent variable is observed as a scrambled response using Eichhorn & Hayre's (1983) approach to collecting sensitive personal information. The estimates of the parameters in the model remain unbiased, but the variances of the estimates increase due to scrambling. The Wald test of the null hypothesis H₀: β=β₀, against the alternative hypothesis H_a: β#β₀, is also investigated. Parameter estimates obtained from scrambled responses are compared to those from conventional or direct-question surveys, using simulation. The coverage by nominal 95% confidence intervals is also reported.     

A NOTE ON OPTIMUM STRATIFICATION IN SAMPLING WITH VARYING PROBABILITIES1

Singh and Sukhatme [4] have considered the problem of optimum stratification on an auxiliary variable x when the units from the different strata are selected with probability proportional to the value of the auxiliary variable and the sample sizes for the different strata are determined by using Neyman allocation method. The present paper considers the same problem for the proportional and equal allocation methods. The rules for finding approximately optimum strata boundaries for these two allocation methods have been given. An investigation into the relative efficiency of these allocation methods with respect to the Neyman allocation has also been made. The performance of equal allocation is found to be better than that of proportional allocation and practically equivalent to the Neyman allocation.     

Mixed motivations for migration in the urban prairies: A comparative approach

Two Canadian Prairie cities, with populations of about 600 000 each, have experienced dramatically different growth patterns in the last twenty years because of quite different economic bases. Edmonton has been a fast growth city based on the gas and oil boom. Winnipeg has experienced very slow growth with a very diversified economy. Through the vehicles of the Edmonton and Winnipeg Area Studies, an analysis of migration to the two cities is possible. It is a study of mixed motivation. Not only are single motives rarely expressed by respondents, but the relative strength of economic and family motives in particular is somewhat unexpected in the two cities. Finally, while return migration accounts for 50 percent of migrants to the slow growth city, it is not as detached from economic motives as appears to be the case in other Canadian research on return migration.Revised version of a paper presented at the Canadian Population Society Meeting, Hamilton, Ontario, June, 1987     

Marketing planning in India—A survey

This paper describes the response to a study of the marketing planning function in large-size companies in India and the techniques used to assess the level of sophistication achieved. The authors analyse their findings and conclude that although a high level of sophistication had not yet been achieved, the process was accelerating and there was a positive relationship between the size of the company and its profitability and the accompanying level of marketing planning sophistication.     

The World Fertility Survey: charting global childbearing

Interviewing some 350,000 women in 42 developing countries and 20 developed countries representing nearly 40% of the world's population, the World Fertility Survey (WFS) is in a unique position to document the historic 1970s slowdown in global population growth. This Bulletin describes efforts begun in 1972 to ensure high quality, internationally comparable, accessible data, the data's importance for policymakers, planners and researchers, and major findings available by early 1982 from directly assisted WFS surveys in 29 developing countries and contraceptive use data from WFS-type surveys in 16 developed countries. Marital fertility has declined in all developing regions except Africa but still averages from 4.6 children/woman in Latin America to 6.7 in Africa, while preferred family size ranges from 3.0 children in Turkey to 8.9 in Senegal--far above the average 2.2-2.5 children/woman needed to end developing countries' population growth in the long run. However, women ages 15-19 prefer nearly 2 children fewer than the oldest women ages 45-49; 3.8 vs. 5.7 on the average. Nearly 1/2 (48%) of married women surveyed in 27 countreis said they wanted no more children. Preventing all unwanted births would reduce birth rates up to 15 births/1000 population in these countries. Overall, 32% of married, fecund women in developing countries are using contraception compared to an average 72% in 16 developed countries. Education, literacy, and more available family planning services increase contraceptive use. Age at marriage is rising in Asia, but this factor alone has little effect on fertility. Infant mortality is higher in many developing countries than previously thought. Breastfeeding is an important restraint on fertility in most developing countries but is declining among more educated, employed, and urban women which could raise fertility if not compensated for by gains in contraceptive use.     

Knowing What Your Customer Wants: Improving Inventory Allocation Decisions in Online Movie Rental Systems

In Online Movie Rental Systems, customer desire to rent can often be observed before the actual consumption occurs. Desire represents uncensored (or true) demand information. Hence, the impact of inventory decisions (numbers of physical copies of different movies) can be accurately traced to the creation of desire (via Word‐of‐mouth), and then to rental. Word‐of‐Mouth (WOM) has been recognized as one of the most influential sources of information transmission, especially for experience goods. Poor inventory decisions may result in lost rentals in two ways: One is the loss of rentals because of low inventory (direct effect), and the other is the loss of the possible demand (rentals) that could have been created through WOM (indirect effect). We use data from an online DVD‐by‐mail firm to estimate the direct and indirect effects of inventory decisions, considering the circular relationship: Rental generates WOM, WOM creates Desire, and Desire turns into Rental. We find that the magnitude of indirect effects is significant, comparable to and sometimes even exceeding direct effects. The value of the empirical findings to facilitate better inventory allocation decisions is examined.     

A novel spatial outlier detection technique

Spatial outliers are spatially referenced objects whose non spatial attribute values are significantly different from the corresponding values in their spatial neighborhoods. In other words, a spatial outlier is a local instability or an extreme observation that deviates significantly in its spatial neighborhood, but possibly not be in the entire dataset. In this article, we have proposed a novel spatial outlier detection algorithm, location quotient (LQ) for multiple attributes spatial datasets, and compared its performance with the well-known mean and median algorithms for multiple attributes spatial datasets, in the literature. In particular, we have applied the mean, median, and LQ algorithms on a real dataset and on simulated spatial datasets of 13 different sizes to compare their performances. In addition, we have calculated area under the curve values in all the cases, which shows that our proposed algorithm is more powerful than the mean and median algorithms in almost all the considered cases and also plotted receiver operating characteristic curves in some cases.