A note on estimating regression coefficients with missing data

In this note, we consider the problem of estimating regression coefficients when there are missing observations of some explanatory variables. Following Dagenais (1973), Gourieroux and Monfort (1981), and Conniffe (1983a, 1983b), we assume auxiliary relationships exist among explanatory varibles. Several estimatprs and their interrelationships are discussed. We begin with the model of Gourieroux and

Monfort (1981)     

Effects of Category Order on Answers in Mail and Telephone Surveys1

Abstract Past research suggests that mail surveys encourage a primacy effect, which is a tendency to choose the first answers from a list, whereas telephone surveys encourage a recency effect, a tendency to choose the last answers from a list. This paper summarizes results from 82 new experiments conducted in 12 separate surveys in seven states. Only four of 33 mail survey comparisons exhibited significant primacy effects, while five of 26 experiments in telephone surveys exhibited recency effects. In addition, only three of 23 cross-method comparisons produced a significant primacy/recency effect in the expected manner. The conclusion is that the prevalence of primacy and recency effects has been over-estimated by past research and a new theoretical approach that takes into account multiple causation is needed for examining these effects.     

Summary of the Workshop on Issues in Risk Assessment: Quantitative Methods for Developmental Toxicology

This report summarizes the proceedings of a conference on quantitative methods for assessing the risks of developmental toxicants. The conference was planned by a subcommittee of the National Research Council's Committee on Risk Assessment Methodology ⁴ in conjunction with staff from several federal agencies, including the U.S. Environmental Protection Agency, U.S. Food and Drug Administration, U.S. Consumer Products Safety Commission, and Health and Welfare Canada. Issues discussed at the workshop included computerized techniques for hazard identification, use of human and animal data for defining risks in a clinical setting, relationships between end points in developmental toxicity testing, reference dose calculations for developmental toxicology, analysis of quantitative dose-response data, mechanisms of developmental toxicity, physiologically based pharmacokinetic models, and structure-activity relationships. Although a formal consensus was not sought, many participants favored the evolution of quantitative techniques for developmental toxicology risk assessment, including the replacement of lowest observed adverse effect levels (LOAELs) and no observed adverse effect levels (NOAELs) with the benchmark dose methodology.     

Tearoom trade: A research update

Conclusion Like many studies of covert deviance, this paper is based upon a captive sample of persons who have come to the attention of law enforcement agencies. The existence of Laud Humphreys' research, however, makes possible a comparison of police generated data with data obtained through observations and interviews with unapprehended offenders. Because police observations were so detailed, a rare opportunity to replicate a qualitative study presented itself. This research largely substantiates the picture drawn by Humphreys in his classic study,Tearoom Trade: Impersonal Sex in Public Places. Consistent with his observations, most tearoom participants (a) communicate through non-verbal gestures and seldom speak, (b) do not associate outside the tearoom or attempt to learn one another's identity or exchange biographical information, (c) do not use force or coercion or attempt to involve youths or children, (d) are primarily heterosexual and married, (e) depart separately with the insertor leaving first, (f) commit their sex acts out of sight of the entrance and accidental exposure, (g) do not undress or engage in anal sex, (h) break off sexual contact when someone enters the washroom, (i) rarely approach straight men, (j) read and write sexually explicit homosexual graffiti, and (k) linger inside and outside the washroom for someone to appear. In addition, (1) fellatio is generally not reciprocated and fellators are usually older men; (m) most offenders are neat in appearance; (n) some engage in series and simultaneous encounters; (o) encounters are brief, usually not exceeding twenty minutes; and (p) few have criminal records with the exception of those previously convicted of similar offenses.The behavior of players reveals remarkable consistency over time, from community to community, and across national boundaries. Many men, the majority of them married and primarily heterosexual, continue to visit out-of-the-way public washrooms in search of fast, impersonal, and exciting sex despite the risk to family, friends, job, and reputation. Although shopping malls have usurped public parks as the favorite locale of tearoom participants, the basic rules of the game and profile of the players—as Humphreys contends—remain the same over time and place.     

Nondictatorially independent pairs

Suppose that social welfare function f satisfies the Pareto condition and has complete and transitive values. On a domain satisfying the free quadruple property, if the outcome set X has m< outcomes, then the set of pairs of distinct alternatives on which f satisfies both independence and nondictatorship contains at most the fraction 2/m of all pairs. On a domain satisfying the free six-tuple property, if X is a subset of Euclidean space then the set of pairs on which f satisfies both independence and nondictatorship has Lebesgue measure zero.Campbell's research was financed by the National Science Foundation, grant SES 9209039.     

Touristic authenticity,touristic angst,and modern reality

The tourist has become the symbol of a peculiarly modern type of inauthenticity. This paper explores the criticisms that have been directed at the reality experiences of the tourist. In so doing, the following inexhaustive typology of touristic realities is developed: 1) the first-order or true tourist, 2) the second-order or Angst-ridden tourist, 3( the third-order or anthropological tourist, and 4) the fourth-order or spiritual tourist. Each of these types represents a progressively more intense search for reality through travel. Each is, however, criticized for participating in its own form of inauthenticity.After exploring the reality experiences and criticisms of each of these travellers, the paper turns the tables on the cultured despisers of tourism to argue that perhaps the lowly first-order tourist is not so inauthentic after all. True, this traveller may not be having a real heroic adventure, but such is not the goal. Rather, the reality experienced by the first-order tourist is a pleasurable liberation from the normal concerns of everyday life which simultaneously reaffirms commitment to that reality. Quite frequently the first-order tourist is less concerned about having a real experience in the visited place than in experiencing family and friendship relationships-relationships completely ignored by the anti-touristic tourists in their search for authenticity in someone else's reality.The author would like to thank Peter L. Berger, Harry C. Bredemeier, Warren I. Susman, and M. Kathy Kenyon for their comments and suggestions on earlier versions of this paper. This research was supported in part by NIMH grant no. 5 T32 NH14660.