Towards a theory of point optimal testing

This paper puts the case for the inclusion of point optimal tests in the econometrician's repertoire. They do not suit every testing situation but the current evidence, which is reviewed here, indicates that they can have extremely useful Small-sample power properties. As well as being most powerful at a nominated point in the alternative hypothesis parameter space, they may also have optimum power at a number of other points and indeed be uniformly most powerful when such a test exists. Point optimal tests can also be used to trace out the maxemum attainable power envelope for a given testing problem, thus providing a benchmark against which test procedures can be evaluated. In some cases, point optimal tests can be constructed from tests of simple null hypothesis against a simple alternative. For a wide range of models of interst to econometricians, this paper shows how one can check whether a point optimal test can be constructed in this way. When it cannot, one may wish to consider approximately point optimal tests. As an illustration, the approach is applied to the non-nested problem of testing for AR(1) distrubances against MA(1) distrubances in the linear regression model.     

The application of the durbin-watson test to the dynamic regression model under normal and non-normal errors

Until recently, a difficulty with applying the Durbin-Watson (DW) test to the dynamic linear regression model has been the lack of appropriate critical values. Inder (1986) used a modified small-disturbance distribution (SDD) to find approximate critical values. King and Wu (1991) showed that the exact SDD of the DW statistic is equivalent to the distribution of the DW statistic from the regression with the lagged dependent variables replaced by their means. Unfortunately, these means are unknown although they could be estimated by the actual variable values. This provides a justification for using the exact critical values of the DW statistic from the regression with the lagged dependent variables treated as non-stochastic regressors. Extensive Monte Carlo experiments are reported in this paper. They show that this approach leads to reasonably accurate critical values, particularly when two lags of the dependent variable are present. Robustness to non-normality is also investigated.     

PHYSICAL PUNISHMENT IN THE HOME IN NEW ZEALAND

Results are reported for a national opinion poll of 1,000 adult New Zealanders which focussed on two questions: what are New Zealand parents currently doing to discipline their children, and what are the current attitudes of New Zealanders towards physical punishment in the home? Changes appear to be occurring in the attitudes and behaviour of New Zealanders toward physical punishment in the home. Although smacking with the hand is still both approved and used as a common parental response to the misbehaviour of children of all ages, anything more severe is no longer part of the repertoire of most parents or the experience of most children. Further evidence of change is provided by data on difference among the groups in the sample. Younger parents, current parents and the more highly educated are less likely to report using and endorsing the more severe forms of physical punishment that those who are older, have never had children or who have less education. Unlike the reported child-rearing practices of 30 years ago, parents today appear to be making use of a range of non-physical responses to misbehaviour and are more frequently explaining or discussing matters with their children.     

CRITICAL VALUE APPROXIMATIONS FOR TESTS OF LINEAR REGRESSION DISTURBANCES

Two important classes of tests for non-spherical disturbances in the linear regression model involve test statistics whose null distributions and hence critical values depend on the regressors. This paper investigates the accuracy of the normal, two moment beta and four moment beta approximations to the critical values of such tests. An empirical experiment aimed at evaluating the accuracy of the approximations for a variety of tests against autocorrelation and heteroscedasticity is conducted. Overall the approximations are found to provide reasonably accurate critical values with skewness being a factor determining the degree of accuracy.     

How do health professionals support pregnant and young mothers in the community? A selective review of the research literature

BackgroundThe cultural phenomenon of “teenage pregnancy and motherhood” has been socially constructed and (mis)represented in social and health care discourses for several decades. Despite a growing body of qualitative research that presents an alternative and positive view of young motherhood, there remains a significant gap between pregnant and young women's experience of young motherhood and current global health and social policy that directs service delivery and practice.AimThis paper aims to heighten awareness of how a negative social construction of young motherhood influences global health and social policy that directs current community health models of practice and care for young mothers in the community.DiscussionThere is clear evidence on the vital role social support plays in young women's experience of pregnancy and motherhood, particularly in forming a positive motherhood identity. This discussion paper calls us to start open and honest dialogue on how we may begin to re-vision the ‘deficit view’ of young motherhood in order to address this contradiction between research evidence, policy discourse and current practice and service provision. Qualitative research that privileges young women's voices by considering the multidimensional experiences of young motherhood is an important step towards moving away from universally prescribed interventions to a non-standard approach that fosters relational and responsive relationships with young mothers that includes addressing the immediate needs of young mothers at the particular time.