Cross-sectional research is research which makes observations at only one period in time. Examples include conducting a survey or opinion poll. Cross-sectional research is analogous to taking one still picture of the population or group being investigated. Longitudinal research, on the other hand, makes more than one set of observations and can be compared to a simple moving picture.
In cross-sectional research, data are collected from the research participants at a single point in time or during a single, relatively brief time period. The data are typically collected from multiple groups or types of people in cross-sectional research. For example, data in a cross-sectional research study might be collected from males and females, from people in different socioeconomic status, from multiple age groups, and from people with different abilities and accomplishments.
The major advantage of cross-sectional research is that data can be collected on many different kinds of people in a relatively short period of time. Cross-sectional research has several weaknesses. One disadvantage is that it is difficult to establish time order (condition 2 of the necessary condition for causality).
Time order can be partially established in cross-sectional research through theory, through past research findings, and through an understanding of the independent variable (you can safely assume that an adults biological sex occurs before the amount of education they have because biological sex is set at birth). These techniques for establishing time order are weaker than actually observing people over time. A related disadvantage is that the study of developmental trends can be misleading when using cross-sectional research data.
The Internet and Social Participation:
Contrasting Cross-Sectional Research and Longitudinal Analyses - Irina
Shklovski, Robert Kraut, Lee Rainie.
Abstract: Changes in the way people communicate are important, because communication is the mechanism people use to develop and maintain social relationships, so valuable for their physical and mental health. This paper uses data from a national panel study / panel survey conducted in 2000 and 2001 to examine the influence of Internet use on communication and on social involvement. It contrasts the conclusions one can draw from cross-sectional research and longitudinal research data on these issues. Longitudinal analyses provide stronger evidence of the causal effects of using the Internet than do the cross-sectional research ones. The longitudinal data show that heavy use of the Internet is associated with reductions in the likelihood of visiting family or friends on a randomly selected day. Cross-sectional research analyses show high correlations between the frequency with which respondents communicate with specific family members by visits, phone calls and email, suggesting that communication in one medium stimulates the others.