9 Back/knee strength, gender, and lifting strategy. Human Factors (December 2009) investigated whether back and knee strength dictates the load-lifting strategies of males and females. A sample of 32 healthy adults (16 men and 16 women) participated in a series of strength tests on the back and the knees. Following the tests, the participants were randomly divided into two groups, where each group consisted of 8 men and 8 women. One group was provided with knowledge of their strength test results, while the other group was not provided with this knowledge. The final phase of the study required the participants to lift heavy cast iron plates out of a bin. Based on the different angles used to lift the plates, a quantitative measure of posture—called a postural index—was measured for each participant. The goal of the research was to determine the effect of gender and strength knowledge (provided or not provided) on the mean postural index. For this study, identify each of the following:

a. experimental unit

b. response variable

c. factors

d. levels of each factor

e. treatments