Heteroskedasticity-Robust Inference in Finite Samples

Since the advent of heteroskedasticity-robust standard errors, several papers have proposed adjustments to the original White formulation. We replicate earlier findings that each of these adjusted estimators performs quite poorly in finite samples. We propose a class of alternative heteroskedasticity-robust tests of linear hypotheses based on an Edgeworth expansions of the test statistic distribution. Our preferred test outperforms existing methods in both size and power for low, moderate, and severe levels of heteroskedasticity.

Heteroskedasticity-robust inference in finite samples

Since the advent of heteroskedasticity-robust standard errors, several papers have proposed adjustments to the original White formulation. We replicate earlier findings that each of these adjusted estimators performs quite poorly in finite samples. We propose a class of alternative heteroskedasticity-robust tests of linear hypotheses based on an Edgeworth expansion of the test statistic distribution. Our preferred test outperforms existing methods in both size and power for low, moderate, and severe levels of heteroskedasticity.National Science Foundation (U.S.). Graduate Research Fellowship (Grant 0645960

Harding College Spring Sing Program 1977

Program for the 1977 Spring Sing performance at Harding College. Hosts and Hostesses: Carol Jeannette Curtis, Kenneth Hershel Dowdy, Katrina Lou Wilson, James Timothy Woodroofhttps://scholarworks.harding.edu/spring-sing/1003/thumbnail.jp

Howard Tumber, Frank Webster, Journalists Under Fire. Information War and Journalistic Practices | Brian McNair, Cultural Chaos. Journalism, News and Power in a Globalised World

Deux livres britanniques récents traitent d’un thème similaire : l’analyse des liens entre les médias et les processus de globalisation et de mondialisation, surtout dans des situations conflictuelles. Tous deux le font aussi à partir d’un point de vue semblable : le nouveau système médiatique serait caractérisé par le chaos, que le terme soit pris dans un sens scientifique, comme le fait Brian McNair, ou selon le sens commun comme le font Howard Tumber et Frank Webster Selon Brian McNair, le..

Aeron Davis, Public Relations Democracy. Public Relations, Politics and the Mass Media in Britain

Thème fondamental dans la médiologie anglo-saxonne, l'analyse des négociations en amont relate systématiquement des activités des attachés de presse. Toutefois, les analyses qui recensent dans le détail les interactions entre ceux-ci et les journalistes sont rares. Pendant longtemps, la tradition anglo-saxonne a été dominée par une série d'études qui insistaient sur le rôle dominant des sources dans les négociations en amont – revenant à appuyer une thèse marxiste – ou marxisante – selon laqu..

Mondes arabophones et médias

Si s’intéresser aux médias arabophones n’est pas nouveau, les attaques du 11-Septembre aux États-Unis ont accentué et élargi l’intérêt porté publiquement à tout ce qui concerne l’opinion des populations arabophones ou, plus largement, islamiques. D’ailleurs, il a nourri nombre de recueils ou de dossiers universitaires récents (Ayish, 2003 ; Hafez, 2001 ; Hafez, 2002 ; Schlesinger, Mowlana, 1993 ; Middle East Report, 1993 ; Middle East Journal, 2000 ; Sakr, 2001) qui, par exemple, ont traité d..

Le conflit Israélo-Palestinien : médias occidentaux, « revendications de vérité » et antisionisme

À partir de l’analyse de la couverture médiatique d’événements individuels, il est possible de démontrer des biais réciproques. Il faudrait plutôt partir d’une analyse systématique d’un échantillon aussi représentatif que possible. Les analystes anglo-saxons des médias anglophones montrent que, là où il y a un biais pour ou contre Israël ou la cause palestinienne, ces médias penchent plutôt du côté israélien, même si la marge de préférence s’est réduite sur une période de 25 ans. Du point de vue méthodologique, ces études sont fondées soit sur la revendication d’une vérité qui démontrerait la nature fautive ou lacunaire des comptes rendus médiatiques, soit sur la démonstration de l’exclusion d’opinions pertinentes, ce qui ferait d’une partialité incompatible avec le devoir de représentativité. Pour des raisons historiques, le biais en question se lie potentiellement à la légitimation de l’État d’Israël, donc à la relation controversée entre l’antisionisme et l’antisémitisme.The analysis of the media coverage of individual events easily leads to the assertion of opposite biases. It is preferable to start from the systematic analysis of a sample as representative as possible. Anglo-US analyses of English language media show that where there is bias for or against Israel or the Palestinian cause, these media have tended to favour the Israeli side, even if the margin of preference has been reduced over the last 25 years. Methodologically, these studies are based either on a truth claim that is held to show how the media version of events is partial or incorrect, or on the demonstration of exclusion of relevant points of view, which shows a lack of representative coverage, basic to media performance. For historical reasons, this type of bias is potentially linked to the legitimacy of the state of Israel, and therefore to the controversial relationship between anti-zionism and anti-semitism

Arabic-Speaking Worlds and Media

Interest in Arabic media is nothing new, but the 11 September 2001 attacks in the United States heightened and broadened publicly stated interest in relation to public opinion in Arabic and, more generally, Islamic countries, including in numerous recent academic publications and collections (Ayish, 2003; Hafez, 2001; Hafez, 2002; Schlesinger, Mowlana, 1993 ; Middle East Report, 1993; Middle East Journal, 2000; Sakr, 2001). These have addressed, for example, Arabic media systems, representati..

The influence of body mass index and age on C-peptide at the diagnosis of type 1 diabetes in children who participated in the diabetes prevention trial-type 1

BACKGROUND/OBJECTIVE: The extent of influence of BMI and age on C-peptide at the diagnosis of type 1 diabetes (T1D) is unknown. We thus studied the impact of body mass index Z-scores (BMIZ) and age on C-peptide measures at and soon after the diagnosis of T1D. METHODS: Data from Diabetes Prevention Trial-Type 1 (DPT-1) participants <18.0 years at diagnosis was analyzed. Analyses examined associations of C-peptide measures with BMIZ and age in 2 cohorts: oral glucose tolerance tests (OGTTs) at diagnosis (n = 99) and mixed meal tolerance tests (MMTTs) <6 months after diagnosis (n = 80). Multivariable linear regression was utilized. RESULTS: Fasting and area under the curve (AUC) C-peptide from OGTTs (n = 99) at diagnosis and MMTTs (n = 80) after diagnosis were positively associated with BMIZ and age (P < .001 for all). Associations persisted when BMIZ and age were included as independent variables in regression models (P < .001 for all). BMIZ and age explained 31%-47% of the variance of C-peptide measures. In an example, 2 individuals with identical AUC C-peptide values had an approximate 5-fold difference in values after adjustments for BMIZ and age. The association between fasting glucose and C-peptide decreased markedly when fasting C-peptide values were adjusted (r = 0.30, P < .01 to r = 0.07, n.s.). CONCLUSIONS: C-peptide measures are strongly and independently related to BMIZ and age at and soon after the diagnosis of T1D. Adjustments for BMIZ and age cause substantial changes in C-peptide values, and impact the association between glycemia and C-peptide. Such adjustments can improve assessments of β-cell impairment at diagnosis