Plan and Operation of the NHANES II Mortality Study

Abstract

Objectives
The NHANES II Mortality Study is a prospective study of adult participants examined in the second National Health and Nutrition Examination Survey (NHANES II) conducted between 1976 and 1980. It was designed to investigate the association between factors measured at baseline and mortality. The methods used in the study are described and assessed in this report.

Methods
The vital status of NHANES II participants who were 30–75 years of age at their examination was ascertained after 12–16 years. Vital status was assessed by searching the National Death Index and the Social Security Administration Death Master File for deaths occurring in the United States. Causes of death were obtained from the National Center for Health Statistics Multiple Cause of Death file or death certificates. To assess how well mortality was ascertained, the survival of the cohort after 5 and 10 years was compared to that of the U.S. population during the same period.

Results
As of December 31, 1992, 23.2 percent of the 9,250 cohort members were found to be deceased.
The remaining 76.8 percent that were not found to be deceased may be assumed to be alive for analytic purposes. Cumulative survival probabilities for the cohort were generally higher than probabilities calculated from U.S. life table data. Although some differences were expected, these data suggest that after 10 years of follow-up using passive methods, mortality may have been under ascertained for the cohort. Discrepancies between the survival patterns for NHANES II cohort and U.S. vital statistics were larger for black than for white participants, indicating that ascertainment of mortality was poorer among black participants. Researchers using the NHANES II Mortality Study, 1992 data should be aware of these study limitations.

Keywords: Epidemiologic methods, data collection c health surveys, cohort studies, longitudinal study, follow-up studies.

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Plan and Operation of Cycle 6 of the National Survey of Family Growth

Abstract

Objectives
This report describes how Cycle 6 of the National Survey of Family Growth (NSFG) was designed, planned, and implemented. The NSFG is a national survey of women and men 15–44 years of age designed to provide national estimates of factors affecting pregnancy and birth rates; men’s and women’s health; and parenting. Cycle 6, conducted in 2002, was the first time the NSFG included a sample of males.

Methods
The survey used in-person, face-to-face interviews conducted by trained female interviewers. One person per household was interviewed from a national area probability sample in about 120 sample areas, with oversamples of teenagers, African Americans, and Hispanics. The data collection used computer-assisted personal interviewing (CAPI). Separate questionnaires were used for female and male respondents. The last section of the questionnaires used a technique called audio computer-assisted self-interviewing (ACASI). In order to control costs and nonresponse errors, survey managers statistically analyzed results from interviewers’ visits to sampled households each day, and used those results to allocate interviewer labor and other resources more efficiently. This management improved response rates and made the sample more representative.

Results
Over 12,500 interviews were completed, about 7,600 with females and about 4,900 with males. The response rate was about 80 percent for females and about 78 percent for males. The survey procedures were adapted during the fieldwork to achieve the desired response rates and to control costs.

Keywords: Computer-assisted personal interviewing (CAPI) c survey methodology c response rates c audio computer-assisted self-interviewing (ACASI) c eligibility rate c National Survey of Family Growth .

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Teaching Introductory Statistics Online – Satisfying the Students

Gail E. Tudor

Husson College

Abstract

This paper describes the components of a successful, online, introductory statistics course and shares students’ comments and evaluations of each component. Past studies have shown that quality interaction with the professor is lacking in many online courses. While students want a course that is well organized and easy to follow, they also want to interact with the professor and other students. Interactions in this course took place through small group discussions, emails, weekly announcements and graded exams. The course also contained lecture slides with audio prepared by the professor. As the variety and quantity of interaction increased, student satisfaction with the amount of interaction with the professor increased from 75% the first year of the course to 99% the fifth year. Overall satisfaction with the online course increased from 93% the first year to 100% the fifth year.

Keywords: Course design; Online versus traditional learning; Statistics education.

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Attitudes Toward Statistics and Their Relationship with Short- and Long-Term Exam Results

Stijn Vanhoof

Ana Elisa Castro Sotos

Patrick Onghena

Lieven Verschaffel

Wim Van Dooren

Wim Van den Noortgate

Katholieke Universiteit Leuven
Journal of Statistics Education Volume 14, Number 3 (2006),

Abstract

This study uses the Attitudes Toward Statistics (ATS) scale (Wise 1985) to investigate the attitudes toward statistics and the relationship of those attitudes with short- and long-term statistics exam results for university students taking statistics courses in a five year Educational Sciences curriculum. Compared to the findings from previous studies, the results indicate that the sample of undergraduate students have relatively negative attitudes toward the use of statistics in their field of study but relatively positive attitudes toward the course of statistics in which they are enrolled. Similar to other studies, we find a relationship between the attitudes toward the course and the results on the first year statistics exam. Additionally, we investigate the relationship between the attitudes and the long-term exam results. A positive relationship is found between students’ attitudes toward the use of statistics in their field of study and the dissertation grade. This relationship does not differ systematically from the one between the first year statistics exam results and the dissertation grade in the fifth year. Thus, the affective and cognitive measures at the beginning of the curriculum are equally predictive for long-term exam results. Finally, this study reveals that the relationship between attitudes toward statistics and exam results is content-specific: We do not find a relationship between attitudes and general exam results, only between attitudes and results on statistics exams.

Keywords: Assessment; Attitudes Toward Statistics scale.

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Classroom Research: Assessment of Student Understanding of Sampling Distributions of Means and the Central Limit Theorem in Post-Calculus Probability

M. Leigh Lunsford - Longwood University
Ginger Holmes Rowell - Middle Tennessee State University
Tracy Goodson-Espy - Appalachian State University

Abstract

We applied a classroom research model to investigate student understanding of sampling distributions of sample means and the Central Limit Theorem in post-calculus introductory probability and statistics courses. Using a quantitative assessment tool developed by previous researchers and a qualitative assessment tool developed by the authors, we embarked on data exploration of our students’ responses on these assessments. We observed various trends regarding their understanding of the concepts including results that were consistent with research completed previously (by other authors) for algebra-based introductory level statistics students. We also used the information obtained from our data exploration and our experiences in the classroom to examine and conjecture about possible reasons for our results.

Keywords: Action Research.

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An Active Tutorial on Distance Sampling

Alice Richardson - University of Canberra

Abstract

The technique of distance sampling is widely used to monitor biological populations. This paper documents an in-class activity to introduce students to the concepts and the mechanics of distance sampling in a simple situation that is relevant to their own experiences. Preparation details are described. Variations and extensions to the activity are also suggested.

Keywords: Estimation; Proportions; Sampling distribution; Statistical education.

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Probability in Action: the Red Traffic Light

John A. Shanks University of Otago
Journal of Statistics Education Volume 15, Number 1 (2007),

Abstract

Emphasis on problem solving in mathematics has gained considerable attention in recent years. While statistics teaching has always been problem driven, the same cannot be said for the teaching of probability where discrete examples involving coins and playing cards are often the norm. This article describes an application of simple probability distributions to a practical problem involving a car’s approach to a red traffic light, and draws on the ideas of density functions, expected value and conditional distributions. It provides a valuable exercise in applying theory in a practical context.

Keywords: Distributions; Modelling; Optimization; Problem solving.

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A Bubble Mixture Experiment Project for Use in an Advanced Design of Experiments Class

Stefan H. Steiner - University of Waterloo
Michael Hamada - Los Alamos National Laboratory
Bethany J. Giddings White - University of Waterloo
Vadim Kutsyy - Guardian Analytics
Sofia Mosesova - University of Waterloo
Geoffrey Salloum - Camosun College

Journal of Statistics Education Volume 15, Number 1 (2007)

Abstract

This article gives an example of how student-conducted experiments can enhance a course in the design of experiments. We focus on a project whose aim is to find a good mixture of water, soap and glycerin for making soap bubbles. This project is relatively straightforward to implement and understand. At its most basic level the project introduces students to mixture experiments and general issues in experimental design such as choosing and measuring an appropriate response, selecting a design, the effect of using repeats versus replicates, model building, making predictions, etc. To accommodate more advanced students, the project can be easily enhanced to draw on various areas of statistics, such as generalized linear models, robust design, and optimal design. Therefore it is ideal for a graduate level course as it encourages students to look beyond the basics presented in class.

Keywords: Constrained experimental region; Generalized linear model; Optimal design; Poisson regression; Robust parameter design.

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