Journal Article

  • This article reports on the results of two studies that investigated the effectiveness of different uses of expert systems in large introductory statistics classes. Three groups of students were compared -- those who used an expert system created by the instructor of the course, those who created their own expert system, and those who did not use any at all. The first experiment showed non-significant, but interesting, trends that were explored in the second experiment. In the second experiment, significant differences emerged as the semester evolved in favor of those who used the expert system, regardless of whether or not the students created it themselves. These differences disappeared on the final exam, when technological problems added to the end-of-the-semester tension. These findings support the notion that the use of expert systems in the classroom can have an important impact on the level and amount of learning that occurs. This article describes these two studies in detail and draws some implications for teaching.

  • Using data from the 1997 Digest of Education Statistics, this teaching case addresses the relationship between public school expenditures and academic performance, as measured by the SAT. While an initial scatterplot shows that SAT performance is lower, on average, in high-spending states than in low-spending states, this statistical relationship is misleading because of an omitted variable. Once the percentage of students taking the exam is controlled for, the relationship between spending and performance reverses to become both positive and statistically significant. This exercise is ideally suited for classroom discussion in an elementary statistics or research methods course, giving students an opportunity to test common assumptions made in the news media regarding equity in public school expenditures.

  • This dataset contains observations on five groups of male fruitflies -- 25 fruitflies in each group -- from an experiment designed to test if increased reproduction reduces longevity for male fruitflies. (Such a cost has already been established for females.) The five groups are: males forced to live alone, males assigned to live with one or eight interested females, and males assigned to live with one or eight non-receptive females. The observations on each fly were longevity, thorax length, and the percentage of each day spent sleeping. The structure of the experiment provokes lively discussion on experimental design and on contrasts, and gives students opportunities to understand and verbalize what we mean by the term "statistical interaction." Because the variable thorax length has a strong effect on survival, it is important to take it into account to increase the precision of between-group contrasts, even though it is distributed similarly across groups. The dataset can also be used to illustrate techniques of survival analysis.

  • The dataset bestbuy.dat contains actual monthly data on computer usage (Millions of Instructions Per Second, MIPS) and total number of stores from August 1996 to July 2000. Additionally, information on the planned number of stores through December 2001 is available. This dataset can be used to compare time-series forecasting with trend and seasonality components and causal forecasting based on simple linear regression. The simple linear regression model exhibits unequal error variances, suggesting a transformation of the dependent variable.

  • Body girth measurements and skeletal diameter measurements, as well as age, weight, height and gender, are given for 507 physically active individuals - 247 men and 260 women. These data can be used to provide statistics students practice in the art of data analysis. Such analyses range from simple descriptive displays to more complicated multivariate analyses such as multiple regression and discriminant analysis.

  • Unlike primary and secondary educators, professors in post-secondary education are not required to meet certification requirements in education. Expressly, they are not required to have demonstrated competencies in the areas of education that contribute to the process of educating undergraduate and graduate students, such as pedagogy or evaluation in a subject matter area. To address its responsibility for training graduate students as teachers as well as scholars and investigators, the Emory University Graduate School of Arts and Sciences implemented the Teaching Assistant and Teacher Training Opportunity (TATTO) for all graduate students in 1992. Each graduate department has instituted its own TATTO program with a consistent and Graduate School-approved format. In this paper we describe our experience over the last six years with the evolving teacher-training program in the Department of Biostatistics. In our program, we focus on developing communication skills for all graduates, even those who may not pursue an academic career involving teaching. We also discuss the merits and challenges of our course in pedagogy in biostatistics, as well as other training components, including instruction in statistical consultation. We have found that the interactive dynamic nature of this program is well-received by the students. We have also found that the students benefit from observing good teachers, with attention to the craft of teaching, and from the feedback given by these teachers on student teaching style.

  • The purpose of the study was to develop a valid and reliable test instrument to identify students who hold misconceptions about probability. A total of 263 students completed a multiple-choice test that used a two-part format rather than the typical one-part format. Results of the study showed that even students with formal instruction in statistics continue to demonstrate misconceptions. The test instrument developed in this study provides instructors with (1) a valid and reliable method of identifying students who hold common misconceptions about probability, and (2) diagnostic information concerning students' errors not frequently available through other formats. The test instrument was further evaluated in an instructional intervention study.

  • The statistical power of an experiment is a subtle idea that is difficult to explain to a non-statistician, and yet it is fundamental to the design of scientific experiments. We have developed some spreadsheets that have been useful in illustrating the ideas by simulation. These allow scientists to simulate situations using parameters similar to what they expect in their own work, and to explore the effect of experimental variability. Our examples are available on the World Wide Web.

  • Presents several problems that use calculator or computer-generated graphs of the absolute value function as related to the maximum and minimum functions to illustrate the statistical concepts of range, median, mean, and variance. (MDH)

  • This paper presents a survey of the reported research about students' errors, difficulties and conceptions concerning elementary statistical concepts. Information related to the learning processes is essential to curricular design in this branch of mathematics. In particular, the identification of errors and difficulties which students display is needed in order to organize statistical training programmes and to prepare didactical situations which allow the students to overcome their cognitive obstacles. This paper does not attempt to report on probability concepts, an area which has received much attention, but concentrates on other statistical concepts, which have received little attention hitherto. (orig.)

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