Suppose we randomly selected 250 people, and on the basis of their responses to a survey we assigned them to one of two groups: high-risk group and low-risk group. We then recorded the blood pressure for the members of each group. Such data are called

Matched or paired data

Step-by-step explanation:

In statistics the different types of study included experimental and observational with the matched or paired data.

The observational study is one in which there is no alteration in the obseravtions or any change. It is purely based on observations.

The experimental study is one in which some experiment or change is brought about to see the effects of the experiment and the results are recorded as before and after treatment etc.

The matched or paired study is one in which two or more groups are simultaneously observed , recorded to find the difference between them or other parameters which maybe useful for the differences or similarities.