Descriptive statistics describe trends or the actions of people. For example, statistics show a greater percentage of divorce, taking into account the increased population, indicating that a greater percentage of couples are dissolving their marriage unions, regardless of the fact that there is a greater pool of married persons to draw data from. These are data which indicate a trend that can be interpreted by analysis of the data.
Reliability refers to the degree that an experiment/instrument will give the same (or nearly the same) results when retested, using the same respondent, over time. An instrument that gave widely different scores from one administration to the next would be unreliable. No one would use an intelligence test that said today I was a genius, and next week that I was retarded. Reliability is a relative term, meaning that reliability is not a ...
Basic definitions of and discussion of statistics, reliability and validity, and the difference between norm and criterion referenced tests. Examples.