Question

Statistical tests: For each scenario below, identify the type of test you should use for the analysis.

79. Analyzing the effects of a drug on blood pressure level in a study with 20 people. All 20 people are tested both before taking the drug and after taking the drug.

a) paired t-test

b) unpaired t-test

c) c² test (chi-squared test)

80. Analyzing the effects of a drug on blood pressure level in a study with 30 people. 15 people take the drug and the other 15 people take the placebo.

a) paired t-test

b) unpaired t-test

c) c² test (chi-squared test)

81. Analyzing the effects on pollution on plant size in 10 different regions in the US. In each region, 20 plants exposed to pollution are measured and 20 plants not exposed to pollution are measured.

a) paired t-test

b) unpaired t-test

c) c² test (chi-squared test)

Answer 1

The answer of the question no 79 is-

The scenario that is mentioned in this question can be analysed by using "paired t-test".

Because, in case of two groups that are related (i.e. when two groups are actually same) With the help of paired t-test , we mainly try to find out if any significant difference in the averages of these groups is present or not . In the paired t-test , same population is evaluated before and after a particular incidence (Such as before and after treating with a particular drug) and as a result, in this case, same population is evaluated two times.The scenario that is mentioned in this question is  the same group of people (20 people) is tested before taking the particular drug and after taking that particular drug to find out if there is any effect (significant difference) of that particular drug on blood pressure on that population(20 people) or not. So, the scenario can be analysed by using paired t-test.

The answer of the question no 80 is-

The scenario that is mentioned in this question can be analysed by using "unpaired t-test".

Because, in case of two groups that are not related (i.e. when two groups are completely different ) with the help of unpaired t-test , we mainly try to find out if any significant difference (such as effect of a drug) in the averages of these two groups is present or not. The scenario that is mentioned in this question also has two unrelated groups ( one is the group of people who has taken the drug and another is the group of people who has taken placebo) and so, to analyze the effects of the drug on blood pressure level in a study with 30 people (Which are divided into two unrelated groups), we can use unpaired t-test.

The answer of the question no 81 is-

The scenario that is mentioned in this question can be analysed by using " C² test or Chi- squared test"

Because, When there is large populations ,with the help of chi -squared test ,we can compare the occurrence of a particular character among different populations. The scenario that is mentioned in this question also represents big populations ( populations of plants of 10 different regions in the US and in each region 20 plants exposed to pollution are measured and 20 plants not exposed to pollutions are measured).And the effect of pollution on plant size( particular character) in such large populations of plants can be analysed by using chi-squared test.