Biostatistics Homework 1

The data below come from Carnegie Mellon StatLib, a repository for statistical data sets. I copied the data and the basic story behind the data from:

The story behind the data is as follows: The data are the results of an experiment to test whether directed reading activities in the classroom help elementary school students improve aspects of their reading ability. A treatment class of 21 third-grade students participated in these activities for eight weeks, and a control class of 23 third-graders followed the same curriculum without the activities. After the eight-week period, students in both classes took a Degree of Reading Power (DRP) test which measures the aspects of reading ability that the treatment is designed to improve. Original source: Schmitt, Maribeth C., The Effects on an Elaborated Directed Reading Activity on the Metacomprehension Skills of Third Graders, Ph.D. dissertaion, Purdue University, 1987.

  1. Set of the statistical hypothesis test. What is the null hyphothesis? What is the alternative hypothesis? You can write these out has H0 and Ha but then translate that mathematical formulation into an English sentence.
  2. Should the test be one or two-sided? You answer this question BEFORE seeing the data.
  3. Carry out a 2-sample t-test? What is the value of the t-test statistic? What is its degrees of freedom? What is its p-value? Are the results significant?
  4. Write one sentence in English summarizing the results.

Treatment	Response
Treated	24
Treated	43
Treated	58
Treated	71
Treated	43
Treated	49
Treated	61
Treated	44
Treated	67
Treated	49
Treated	53
Treated	56
Treated	59
Treated	52
Treated	62
Treated	54
Treated	57
Treated	33
Treated	46
Treated	43
Treated	57
Control	42
Control	43
Control	55
Control	26
Control	62
Control	37
Control	33
Control	41
Control	19
Control	54
Control	20
Control	85
Control	46
Control	10
Control	17
Control	60
Control	53
Control	42
Control	37
Control	42
Control	55
Control	28
Control	48