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Full-Text Articles in Physical Sciences and Mathematics

Optimal Survey Design For Community Intervention Evaluations: Cohort Or Cross-Sectional?, Paula Diehr Dec 1995

Optimal Survey Design For Community Intervention Evaluations: Cohort Or Cross-Sectional?, Paula Diehr

Paula Diehr

Community intervention evaluations that measure changes over time may conduct repeated cross-sectional surveys, follow a cohort of residents over time, or (often) use both designs. Each survey design has implications for precision and cost. To explore these issues, we assume that two waves of surveys are conducted, and that the goal is to estimate change in behavior for people who reside in the community at both times. Cohort designs are shown to provide more accurate estimates (in the sense of lower mean squared error) than cross-sectional estimates if (1) there is strong correlation over time in an individual's behavior at …


Poicen.Sas : Censored Poisson Regression, Joseph Hilbe, Gordon Johnston Jul 1995

Poicen.Sas : Censored Poisson Regression, Joseph Hilbe, Gordon Johnston

Joseph M Hilbe

SAS Macro to estimate censored Poisson data, using method of Hilbe. See Hilbe, Joseph M (2011), Negative Binomial Regression, 2nd ed (Cambridge University Press)


Breaking The Matches In A Paired T-Test For Community Interventions When The Number Of Pairs Is Small, Paula Diehr Jul 1995

Breaking The Matches In A Paired T-Test For Community Interventions When The Number Of Pairs Is Small, Paula Diehr

Paula Diehr

There is considerable interest in community interventions for health promotion, where the community is the experimental unit. Because such interventions are expensive, the number of experimental units (communities) is usually small. Because of the small number of communities involved, investigators often match treatment and control communities on demographic variables before randomization to minimize the possibility of a bad split. Unfortunately, matching has been shown to decrease the power of the design when the number of pairs is small, unless the matching variable is very highly correlated with the outcome variable (in this case, with change in the health behaviour). We …


Including Deaths When Measuring Health Status Over Time, Paula Diehr Apr 1995

Including Deaths When Measuring Health Status Over Time, Paula Diehr

Paula Diehr

Measuring health status over time is problematic when some subjects die, because death does not have a defined value on most health status measures. This situation is different from the usual missing data problem because the health status of the dead is, in a sense, known. We examined eight strategies for incorporating deaths into such analyses using three health status measures taken from two data sets, after which we used computer simulation to explore more fully the effect of deaths. The strategies differed in the amount of influence given to the deaths, varying from none (deaths were discarded) to complete …


Applications Of Extended Thermodynamics ...Part I., Sergey Sobolev Jan 1995

Applications Of Extended Thermodynamics ...Part I., Sergey Sobolev

Sergey Sobolev

No abstract provided.


Book Review: Reasoning Agents In A Dynamic World: The Frame Problem. Kenneth M. Ford And Patrick J. Hayes, Eds.,, Jozsef A. Toth Jan 1995

Book Review: Reasoning Agents In A Dynamic World: The Frame Problem. Kenneth M. Ford And Patrick J. Hayes, Eds.,, Jozsef A. Toth

Jozsef A Toth Ph.D.

No abstract provided.


Seizure Threshold In Electroconvulsive Therapy: I. Initial Seizure Threshold, C. Edward Coffey, Joseph Lucke, Richard D. Weiner, Andrew D. Krystal, Michael Aque Jan 1995

Seizure Threshold In Electroconvulsive Therapy: I. Initial Seizure Threshold, C. Edward Coffey, Joseph Lucke, Richard D. Weiner, Andrew D. Krystal, Michael Aque

Joseph Lucke

We measured initial seizure threshold by means of a structured stimulus dosage titration procedure in a clinical sample of 111 depressed patients undergoing brief-pulse, constantcurrent electroconvulsive therapy (ECT). Initial seizure threshold was approximately 60 millicoumbs (mc) (10 Joules) on average, but varied widely (6-fold) across patients. Initial seizure threshold was predicted by four variables: electrode placement (higher with bilateral), gender (higher in men), age (higher with increasing age), and dynamic impedance (inverse relationship). Use of neuroleptic medication was associated with a lower seizure threshold. EEG seizure duration was inversely related to initial seizure threshold, but no other relations with seizure …


Seizure Threshold In Electroconvulsive Therapy (Ect): Ii. The Anticonvulsant Effect Of Ect, C. Edward Coffey, Joseph Lucke, Richard D. Weiner, Andrew D. Krystal, Michael Aque Jan 1995

Seizure Threshold In Electroconvulsive Therapy (Ect): Ii. The Anticonvulsant Effect Of Ect, C. Edward Coffey, Joseph Lucke, Richard D. Weiner, Andrew D. Krystal, Michael Aque

Joseph Lucke

To measure the anticonvulsant effects of a course of electroconvulsive therapy (ECT), we used a flexible stimulus dosage titration procedure to estimate seizure threshold at the first and sixth ECT treatments in 62 patients with depression who were undergoing a course of brief pulse, constant current ECT given at moderately suprathreshold stimulus intensity. Seizure threshold increased by approximately 47% on average, but only 35 (56%) of the 62 patients showed a rise in seizure threshold. The rise in seizure threshold was associated with increasing age, but not with gender, stimulus electrode placement, or initial seizure threshold. Dynamic impedance decreased by …


Assessing Sequential Oncogene Amplification In Human Breast Cancer, Laura E. Janocko, Joseph F. Lucke, David W. Groft, Kathryn A. Brown, Charles A. Smith, Agnese A. Pollice, Sarita G. Singh, Robert Yakulis, Robert J. Hartsock, Stanley E. Shackney Jan 1995

Assessing Sequential Oncogene Amplification In Human Breast Cancer, Laura E. Janocko, Joseph F. Lucke, David W. Groft, Kathryn A. Brown, Charles A. Smith, Agnese A. Pollice, Sarita G. Singh, Robert Yakulis, Robert J. Hartsock, Stanley E. Shackney

Joseph Lucke

Studies of amplification and/or overexpression of c-myc, HER-2/neu, and H-ras in breast cancer have shown that each is associated with a poor prognosis. The purpose of this study was to explore the possibility that there is a preferred sequence of amplification of these oncogenes in breast cancer. The frequencies of amplification and patterns of co-amplification of c-myc, HER-2/neu, and H-ras were studied in a group of 84 breast cancers. The data suggested a preferred sequence of amplification that consisted of c-myc amplification-HER-2/neu amplification-H-ras amplification. This model was supported by loglinear analysis. In addition, the levels of amplification of JC-A, a …