Comparing the performance of the tool being used to the performance of tool designed to measure the same thing called a criterion. This is similar to face validity. Reliability is the ability of the tool to consistently measure the phenomena it was designed to measure. The ultimate job of the measurement tool is to measure the data so that it may be interpreted. From this tool, researchers are able to examine the data and develop conclusions from this examination.
Statistics provide the researcher with a way of viewing the data in two ways.
Descriptive statistics describes the shape of the data. Frequency and distribution are forms of descriptive statistics that can provide opportunities for insight. Inferential statistics attempts to make data fit a model. Statistics helps the human mind to comprehend the scattered data as an organized whole. As a result, statistics have developed statistical tools such as average, median, etc. to address this need.