Chapter 6, Problem 6.74RE

(a)

To determine

To explain why confounding would make the results of this study worthless.

Explanation of Solution

Confounding would make the results of this study worthless because we would not be sure which of the confounding variables are responsible for the effects on the response variable.

(b)

To determine

To outline an experimental design to compare the two methods of instruction and then use randomization using table B.

Explanation of Solution

  $\begin{array}{l}\text{Given: 30 students and 2 treatments}\text{.}\\ \text{We randomly assign 15 of the students to group 1, while the remaining students}\\ \text{are in group 2}\text{.}\\ \text{Group 1 will receive regular instructions}\text{.}\\ \text{Group 2 will receive self paced instructions}\text{.}\\ \text{We will compare the average score of the two groups}\text{.}\end{array}$

  $\begin{array}{l}\text{Assign each of the 30 students a unique number between 01 and 30}\text{.}\\ \text{We will start from line 108 at table B}\text{.}\\ \text{Select the first 2 digit number}\text{. If the number is between 01 and 30, then select the corresponding}\\ \text{student, else ignore the number and select the next 2 digit number}\text{. Repeat until 15 unique students}\\ \text{were selected}\text{.}\\ \text{Group 1: 07,20,24,17,09,06,15,23,16,19,18,08,30,27,12}\text{.}\\ \text{Group 2: 01,02,03,04,05,10,11,13,14,21,22,25,26,28,29}\text{.}\end{array}$