Read the reading text. Match the definitions on the right to the key words on the left. Print when you have all correct and then move onto the next exercise
Sociologists try to make their research valid and reliable. Valid research gives a true picture of what is being researched. Reliable research can be repeated - Sociologists using the same methods and can the same data.
Because it would be impossible to research the whole population or even the whole of one social group in society it is necessary to take a sample. This sample has to be representative of the group being studies - this means for instance that the sample needs similar proportions of different ages, gender, class etc. to the wider group