Air pollution-mortality models: A demonstration of the effects of random measurement error

Errors of measurement have long been recognized as a chronic problem in statistical analysis. Although there is a vast statistical literature of multiple regression models estimating the air pollution-mortality relationship, this problem has been largely ignored. It is well known that pollution measures contain error, but the consequences of this error for regression estimates is not known. We use Lave and Seskin's air pollution model to demonstrate the consequences of random measurement error. We assume a range of 0% to 50% of the variance of the pollution measures is due to error. We find large differences in the estimated effects on mortality of the pollution variables as well as the other explanatory variables once this measurement error is taken into account. These results cast doubt on the usual regression estimates of the mortality effects of air pollution. More generally our results demonstrate the consequences of random measurement error in the explanatory variable of a multiple regression analysis and the misleading conclusions that may result in policy research if this error is ignored.     

Relationship between generalizedh-Statistics and polykays

Summary In this paper, relationships between generalizedh-statistics which estimate powers and products of central moments unbiasedly and the polykays by using ordered partitions are established. A table expressing generalizedh-statistics of weight 12 in terms of polykays and vice versa is presented. Expressions of weight less than 12 are obtained from this table.

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Zusammenfassung In der vorliegenden Arbeit wird mittels geordneter Zerlegungen eine Beziehung zwischen verallgemeinerterh-Statistik, welche Potenzen und Produkte von zentralen Momenten erwartungstreu abschätzt, und polykays hergestellt. Eime Tabele mit verallgemeinerterh-Statistik vom Gewicht 12 in polykay-Termen, und umgekehrt, wird gegeben. Gewichtsausdrücke kleiner als 12 werden aus dieser Tabelle gewonnen.

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This research has been supported by a grant from FINEP/Ministério do Planejamento e Coordenacão Geral to the IMUFRJ.     

The generality/specificity issue in consumer innovativeness research

The purpose of the present study was to explore the role of personality in shaping consumer innovativeness by testing a model of the hierarchical relationships between a global (broad or abstract) personality trait, its domain-specific manifestation in a consumer context, and overt consumer behavior. A survey of 465 adult consumers measured global innovativeness, domain-specific innovativeness for two product categories (clothing and electronics) and self-reported purchase of new clothing and electronic items. Three hypotheses were tested. First, global innovativeness is more highly correlated with domain-specific innovativeness than it is with the purchase of new items. Second, domain-specific innovativeness is more highly correlated with the purchase of new items than is global innovativeness. Finally, the association between global innovativeness and new product purchase is mediated by domain-specific innovativeness. All three hypotheses were supported for both product categories.     

Labor force migration, non-labor force migration, and non-employment reasons for migration

This paper documents the extent and nature of non-employment factors in migration. The labor force status of over 18 million recent interstate migrants in the United States and stated reasons for moving reported in several surveys in the U.S. are examined. Labor force migrants are heterogeneous in terms of the relationships between acquisition of employment and the migration decision, and in terms of the influence of decision makers outside of the migrant household including firms and the government. Numerically important categories of migrants not traditionally captured in migration models exist, including the elderly, the military, and movers from abroad. Whereas non-employment reasons are secondary to employment reasons for a majority of labor force migrants, non-employment factors are singularly important or operate in combination with employment factors for the majority of all migrants. The heterogeneity of migrant types and migration reasons needs to be better captured in migration models.     

On UMV-EStimators in survey sampling

Summary The existence of uniformly minimal variance estimators in the class of all linear unbiased estimators of the population total is discussed. Some remarks are given on the concept of necessary bestness.

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Zusammenfassung Es wird die Existenz von Schätzungen mit gleichmäßig minimaler Varianz in der Klasse aller linearen erwartungstreuen Schätzungen des Populationstotales besprochen. Einige Bemerkungen werden zum Begriffi necessary bestness gemacht.

     

Estimation of a non-invertible moving average process: The case of overdifferencing

The effect of differencing all of the variables in a properly specified regression equation is examined. Excessive use of the difference transformation induces a non-invertible moving average (MA) process in the disturbances of the transformed regression. Monte Carlo techniques are used to examine the effects of overdifferencing on the efficiency of regression parameter estimates, inferences based on these estimates, and tests for overdifferenccing based on the estimator of the MA parameter for the disturbances of the differences regression. Overall, the problem of overdifferencing is not serious if careful attention is paid to the properties of the disturbances of regression equations.     

Effect of outliers on the estimation of parameters

Summary The estimation of parameter in the type of distributionf(x)=b x ^{–1 /b} exp (–x ^b (/b),x>0, is considered, when several outliers of the type , ,r=1,2, ...,k, are present in the data. The estimates of as well as of 's are put in the closed form. Special cases, Weibull, Gamma and Exponential are considered for the case of single outlier. Actual estimates are calculated from the generated samples of size 2 and 3 for the Weibull and Exponential.     

Structural instability of the core

Let σ be a q-rule, where any coalition of size q, from the society of size n, is decisive. Let w(n,q)= 2q-n+1 and let W be a smooth ‘policy space’ of dimension w. Let U(W)^N be the space of all smooth profiles on W, endowed with the Whitney topology. It is shown that there exists an ‘instability dimension’ w^*(σ) with 2w^*(σ)w(n,q) such that:

1. (i) if ww^*(σ), and W has no boundary, then the core of σ is empty for a dense set of profiles in U(W)^N (i.e., almost always),

2. (ii) if ww^*(σ)+1, and W has a boundary, then the core of σ is empty, almost always,

3. (iii) if ww^*(σ)+1 then the cycle set is dense in W, almost always,

4. (iv) if ww^*(σ)+2 then the cycle set is also path connected, almost always.

The method of proof is first of all to show that if a point belongs to the core, then certain generalized symmetry conditions in terms of ‘pivotal’ coalitions of size 2q−n must be satisfied. Secondly, it is shown that these symmetry conditions can almost never be satisfied when either W has empty boundary and is of dimension w(n,q) or when W has non-empty boundary and is of dimension w(n,q)+1.