Use the following information to answer the next seven exercises: Studies are often done by pharmaceutical companies to determine the effectiveness of a treatment program. Suppose that a new AIDS antibody drug is currently under study. It is given to patients once the AIDS symptoms have revealed themselves. Of interest is the average (mean) length of time in months patients live once starting the treatment. Two researchers each follow a different set of 40 AIDS patients from the start of treatment until their deaths. The following data (in months) are collected.

Researcher A: 3; 4; 11; 15; 16; 17; 22; 44; 37; 16; 14; 24; 25; 15; 26; 27; 33; 29; 35; 44; 13; 21; 22; 10; 12; 8; 40; 32; 26; 27; 31; 34; 29; 17; 8; 24; 18; 47; 33; 34

Researcher B: 3; 14; 11; 5; 16; 17; 28; 41; 31; 18; 14; 14; 26; 25; 21; 22; 31; 2; 35; 44; 23; 21; 21; 16; 12; 18; 41; 22; 16; 25; 33; 34; 29; 13; 18; 24; 23; 42; 33; 29

List two reasons why the data may differ.

The raw information obtained from the population of interest is referred to as data in statistics. For example, suppose the researcher wants to determine the average income of people in the United States aged 18 to 60. The data is therefore the information gathered regarding the income of people between the ages of 18 and 60.

Because the two researchers use two separate groups of participants in their studies, the data acquired by the two researchers may not be identical. It's also possible that the researchers selected the respondents for their various studies on their own. As a result, there's a good chance of getting different sets of data from the two groups.

Hence, the following are two reasons that may be possible:

1. The ratio of males to females in the two research groups is the second explanation, as medicine may affect males and females differently.
2. The medicine has varying effects on people of different ages. It's also impossible to find persons in both research groups who are the same age. As a result, the data discrepancy is to be expected.