Question

Evaluate the differences between dependent and independent samples. Provide an example of each type of sample, one that does not deal with a new drug.

Answer 1

If we take paired measurement on same sets of items then that sample will be called dependent sample. Indepent sample are those where we take same measurements on two different sets of sample.

For hypothesis testing the test statistic is different for two samples. Like two independent sample we use the two sample t test but for dependent sample we will use paired t test.

If the values in one sample affects the value of other sample then that sample are dependent sample. But if the values of one sample does not depend on the other sample then that sample is called independent sample.

Example : suppose we want to see whether a drug is effective for reducing blood pressure.

First we apply a drug on a group of persons. Then we measure blood pressure and then compare the blood pressure before and after applying drug. Here the measurement of blood pressure is a dependent sample as they are measured over the same group of people.

Now for independent sample we take two group of people. Then apply one drug to the first group and another drug to the second group. Now after applying the drug we compare which drug is more effective by collecting the blood pressure from two groups of people. Here the samples are independent sample because the blood pressure are measured from two different groups of people.