Question

Evaluate the differences between dependent and independent samples. Provide an example of each type of sample.

Answer 1

Dependent Samples - Two samples are considered to be dependent if we can use the information contained in the first sample to say something about the second sample i.e. if the members in the first sample can be used to determine/retrieve information about the second sample. These are basically paired measurements for a set of data. For example - Consider a study in which we have to see the effect of a drug on a group of participants over a period of 4 months. We collect their say blood pressure readings before the starting of the trial and after the end of the trial. The BP measurements collected at the end of the trial would be then dependent upon the BP readings at the beginning of the trial since we are administrating the drug to the same individual. This is an example of dependent samples.

Independent samples - Two samples are said to be independent if we cannot use the information in the first sample to retrieve information about the second sample. In other words, independent samples are selected randomly so that individual observations are independent of each other. For example - We have data pertaining to an experiment to determine the speed of light that was conducted 40 years ago using a particular set of apparatus. Now we are conducting the same experiment to determine the speed of light using a different set of apparatus & conditions. The observations from the two set of samples are independent of each other since the methodology are different & time lag is significant.

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