Question

1. Researchers examined the relationship between cola consumption and bone loss after fifty. One thousand women were randomly sampled, everyone's cola consumption was recorded over a two month period of time, and bone density measures were also recorded. Researchers found that the more cola consumed, the lower the level of bone density. They concluded that cola consumption leads to loss of bone density.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity.

2. Researchers examined differences in attitudes towards drinking between high school freshman and high school seniors. 400 students completed questionnaires that included information about drinking attitudes. The researchers found that older students maintained more liberal attitudes towards drinking than younger students. The researchers concluded that attitudes towards drinking and alcohol become more liberal with age.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity

3. Researchers were interested in type of feed on milk production in cows. Two hundred cows were used in the study and randomly assigned to either receive Feed A (a high protein based feed) or Feed B ( a low protein based feed). After three weeks of feed consumption and milk production measurements, it was found that Feed A resulted in higher levels of milk production. The researchers concluded that Feed A may cause increased milk production.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity.

4. Researchers were interested in whether working extra problems on the computer increased students learning of statistics. At the end of the semester, grades were compared between students who had used the computer versus students who had not used the computer during the semester for the class. It was found that the students who had worked the extra problems on the computer had higher course grades than students who did not work the problems. It was concluded that use of the computer with extra problems enhances the learning of statistics and the improvement of grades.

What type of study is this research and why?

Identify the variables.

Evaluation the internal validity.

Answer 1

3)

This is an experimental research study. This is because the researcher attempts to establish a cause and effect relationship and randomly assigns the subjects into different groups.
The independent variable is protein based feed and the dependent variable is milk production.
Since the researchers have used a true experimental design, we can assume that the study is high on internal validity.