## Volume 5, Number 3 (November 1997) ISSN: 1069-1898

## Beth L. Chance, "Experiences with Authentic Assessment Techniques in an Introductory Statistics Course" (58K)

In an effort to align evaluation with new instructional goals, authentic assessment techniques (see, e.g., Archbald and Newmann 1988, Crowley 1993, and Garfield 1994) have recently been introduced in introductory statistics courses at the University of the Pacific. Such techniques include computer lab exercises, term projects with presentations and peer reviews, take-home final exam questions, and student journals. In this article, I discuss the University of the Pacific's goals and experiences with these techniques, along with strategies for more effective implementation. --BLC

Key Words:Computer labs; Journals; Projects; Take-home exams.

## Ruma Falk and Arnold D. Well, "Many Faces of the Correlation Coefficient" (66K)

Some selected interpretations of Pearson's correlation coefficient are considered. Correlation may be interpreted as a measure of closeness to identity of the standardized variables. This interpretation has a psychological appeal in showing that perfect covariation means identity up to positive linearity. It is well known that |r| is the geometric mean of the two slopes of the regression lines. In the 2 x 2 case, each slope reduces to the difference between two conditional probabilities so that |r| equals the geometric mean of these two differences. For bivariate distributions with equal marginals, that satisfy some additional conditions, a nonnegative r conveys the probability that the paired values of the two variables are identical by descent. This interpretation is inspired by the rationale of the genetic coefficient of inbreeding. --RF

Key Words:Association in 2 x 2 table; Correlation as probability; Inbreeding; Regression slopes.

## Gerald Giraud, "Cooperative Learning and Statistics Instruction" (36K)

This study examined the relative effects of cooperative vs. lecture methods of instruction. Two sections of an undergraduate statistics course were studied. Test scores were dependent variables. Students in one section were randomly assigned to cooperative groups. Students in both sections completed assignments and practice problems -- in the cooperative class in groups during class, and in the lecture class individually, outside of class. Students in the cooperative learning class achieved higher test scores. Implications of the study and resulting questions are discussed. --GG

Key Words:Achievement; Attitude; Undergraduates.

## Francisco J. Samaniego and Mitchell R. Watnik, "The Separation Principle in Linear Regression" (55K)

In linear regression problems in which an independent variable is a total of two or more characteristics of interest, it may be possible to improve the fit of a regression equation substantially by regressing against one of two separate components of this sum rather than the sum itself. As motivation for this ``separation principle,'' we provide necessary and sufficient conditions for an increased coefficient of determination. In teaching regression analysis, one might use an example such as the one contained herein, in which the number of wins of Major League Baseball teams is regressed against team payrolls, for the purpose of demonstrating that an investigator can often exploit intuition and/or subject-matter expertise to identify an efficacious separation. --MRW

Key Words:Aggregation; Baseball; Correlation; Independent variable; Projection.

## "Teaching Bits: A Resource for Teachers of Statistics" (44K)

This column features "bits" of information sampled from a variety of sources that may be of interest to teachers of statistics. Bob delMas abstracts information from the literature on teaching and learning statistics, while Bill Peterson summarizes articles from the news and other media that may be used with students to provoke discussions or serve as a basis for classroom activities or student projects. --JG

## Robin H. Lock, "NFL Scores and Pointspreads" (11K)

Four datasets (nfl93.dat.txt, nfl94.dat.txt, nfl95.dat.txt, nfl96.dat.txt) contain National Football League game results for recent seasons. In addition to game scores, the data give oddsmakers' pointspreads and over/under values for each game. --RHL

Key Words:Football; Predictions; Wagering.Editorial Board for Volume 5, Number 3

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