WHAT ARE THE MAJOR TYPES OF SOCIAL RESEARCH?CROSS-SECTIONAL: Observe a collection of people at one time.TIME SERIES: Observe different people at multiple times.PANEL: Observe the exact same people at two or more times.COHORT: Observe people who shared an experience at two or more times.CASE STUDY: Observe a small set intensely across time.February 2011195019851970 1990 20101995 2005Married in 1962 20022006 20111982FIGURE 3 The Time Dimension in Social Research