How we change what others think, feel, believe and do
There are two types of study which take time into account.
A longitudinal study takes place over a period of time, repeatedly examining the same population or situation to determine how it changes over time.
A repeated measures study typically makes relatively few sets of measurement. This may give reason for a relatively complex or expensive measurement that would be more problematic if repeated more often.
Repeated measures may be analyzed with a repeated measures ANOVA.
A time series study makes many measures over time, possibly in separate surveys. Due to the overall quantity of measurement it is usually easier to keep measures simple in a time series, otherwise it can become difficult to undertake.
A trend study selects different samples over time and seeks differences to identify overall population shifts.
A panel study selects a single group and gets them to comment about something at different points in time, often done as a discussion.
A cohort study selects different samples from the same age group and studies their maturation over time.
An approximate longitudinal study compares people of different ages at a single point in time, for example understanding generational differences.
A cross-sectional study takes place at a single point in time, typically sampling a population. The study may be complex, time-bound or both.
If this study proves interesting, it may be done again later, extending it into a repeated-measures longitudinal study.