1.39 Grades and self-concept. Table 1.3 presents data on 78 seventh-grade students in a rural midwestern school. 19 The researcher was interested in the relationship between the students’ “self-concept” and their academic performance. The data we give here include each student’s grade point average (GPA), score on a standard IQ test, and gender, taken from school records. Gender is coded as F for female and M for male. The students are identified only by an observation number (OBS). The missing OBS numbers show that some students dropped out of the study. The final variable is each student’s score on the Piers-Harris Children’s Self-Concept Scale, a psychological test administered by the researcher.
SEVENGR
(a) How many variables does this data set contain? Which are categorical variables and which are quantitative variables?
(b) Make a stemplot of the distribution of GPA, after rounding to the nearest tenth of a point.
(c) Describe the shape, center, and spread of the GPA distribution. Identify any suspected outliers from the overall pattern.
(d) Make a back-to-back stemplot of the rounded GPAs for female and male students. Write a brief comparison of the two distributions.