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ABSTRACT

Social media data are increasingly used by researchers to gain insights on individuals’ behaviors and opinions. Platforms like Twitter provide access to individuals’ postings, networks of friends and followers, and the content to which they are exposed. This article presents the methods and results of an exploratory study to supplement survey data with respondents’ Twitter postings, networks of Twitter friends and followers, and information to which they were exposed about e-cigarettes. Twitter use is important to consider in e-cigarette research and other topics influenced by online information sharing and exposure. Further, Twitter metadata provide direct measures of user’s friends and followers as opposed to survey self-reports. We find that Twitter metadata provide similar information to survey questions on Twitter network size without inducing recall error or other measurement issues. Using sentiment coding and machine learning methods, we find Twitter can elucidate on topics difficult to measure via surveys such as online expressed opinions and network composition. We present and discuss models predicting whether respondents’ tweet positively about e-cigarettes using survey and Twitter data, finding the combined data to provide broader measures than either source alone.  相似文献   
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A substantial degree of uncertainty exists surrounding the reconstruction of events based on memory recall. This form of measurement error affects the performance of structured interviews such as the Composite International Diagnostic Interview (CIDI), an important tool to assess mental health in the community. Measurement error probably explains the discrepancy in estimates between longitudinal studies with repeated assessments (the gold-standard), yielding approximately constant rates of depression, versus cross-sectional studies which often find increasing rates closer in time to the interview. Repeated assessments of current status (or recent history) are more reliable than reconstruction of a person's psychiatric history based on a single interview. In this paper, we demonstrate a method of estimating a time-varying measurement error distribution in the age of onset of an initial depressive episode, as diagnosed by the CIDI, based on an assumption regarding age-specific incidence rates. High-dimensional non-parametric estimation is achieved by the EM-algorithm with smoothing. The method is applied to data from a Norwegian mental health survey in 2000. The measurement error distribution changes dramatically from 1980 to 2000, with increasing variance and greater bias further away in time from the interview. Some influence of the measurement error on already published results is found.  相似文献   
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Theorerms are proved for the maxima and minima of IIRi!/IICj!/T!IIyij ! over r× c contingcncy tables Y=(yij) with row sums R1,…,Rr, column sums C1,…,Cc, and grand total T. These results are imlplemented into the network algorithm of Mehta and Patel (1983) for computing the P-value of Fisher's exact test for unordered r×c contingency tables. The decrease in the amount of computing time can be substantial when the column sums are very different.  相似文献   
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The present investigation explored risk and protective factors for suicidal ideation and behavior in a sub-sample of African American and Latino adolescents (n = 2,626) who participated in the 2004 Centers for Disease Control Youth Violence Survey. Structural equation modeling was used to explore exposure to violence at the community level as a contextual factor that could potentially influence depressive symptomatology, substance abuse, parental support, social support, and suicidality among study participants. Findings indicated that exposure to violence at the community level was not directly related to suicidality among this population of urban adolescents. However, it was directly related with several other variables under study in the model, which in turn were directly related with suicidality. Tests of invariance revealed several across-group differences, particularly by race and gender, in how the identified risk and protective factors in the model related to suicidality. Implications for research and practice with urban, ethnic minority, adolescent populations are discussed.  相似文献   
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