Defined

• Cross sectional research involves collection of data once during a limited amount of time. The opposite of this is a cohort, or longitudinal study, in which the researcher collects multiple data points over a longer period of time. Cross sectional research is usually descriptive rather than experimental. These types of studies are useful for describing a particular effect on a particular population at one point in time.
  
  

Example

• If a researcher wanted to examine how children of different ages attack problem solving situations, he might choose to employ a cross sectional study. With this study he could capture information under similar conditions about children of various ages in a short amount of time. This is preferable to using a longitudinal study in which he would need to follow the same children and assess them at different ages.
  
  

Advantages

• Cross sectional studies take little time and are inexpensive to employ. Because multiple groups are studied, various risk factors and outcomes can be measured during these studies. Because the sample is taken from across a wide section of the population, the prevalence of outcomes can be predicted from cross sectional studies. These studies are helpful for generating hypotheses and inspiring future research. Cross sectional studies also carry no risk of losing subjects during follow up, since there is no follow up to the initial study. Because the study takes a one time snapshot of the subjects, there are fewer ethical considerations that are encountered in longer term studies.
  
  

Disadvantages

• Cross sectional research cannot be used to assess cause and effect. This is due mainly to the lack of control for variables within the study. Since the data is collected only once, the researcher must consider that at another time or under other circumstances, the outcomes may be different. Furthermore, without randomization, there is a possibility that some populations will be overrepresented in the study. Also, long term effects of any treatment or phenomena cannot be determined from a cross sectional study.