Module Components

• Learning Activities

Topics

• Foundations of Research
• Time
• Research Designs
• Theory in Research
• Module 2 Self-Review

NRSG 790 - Methods for Research and Evidence-Based Practice

Module 2: Research Overview and Design

Time in Research

Cross-sectional Study Design

The defining feature of a cross-sectional study is that it can compare different population groups at a single point in time. Think of it in terms of taking a snapshot. Findings are drawn from whatever fits into the frame.

• we might choose to measure cholesterol levels in daily walkers across two age groups, over 40 and under 40, and compare these to cholesterol levels among non-walkers in the same age groups.
• We might even create subgroups for gender. However, we would not consider past or future cholesterol levels, for these would fall outside the frame.
• We would look only at cholesterol levels at one point in time.

The benefit of a cross-sectional study design is that it allows researchers to compare many different variables at the same time. We could, for example, look at age, gender, income and educational level in relation to walking and cholesterol levels, with little or no additional cost.

However, cross-sectional studies may not provide definite information about cause-and-effect relationships; they do not consider what happens before or after the snapshot is taken. Therefore, we can’t know for sure if our daily walkers had low cholesterol levels before taking up their exercise regimes, or if the behavior of daily walking helped to reduce cholesterol levels that previously were high.

Longitudinal Study Design

In a longitudinal study, researchers conduct several observations of the same subjects over a period of time, sometimes lasting many years. The benefit of a longitudinal study is that researchers are able to detect developments or changes in the characteristics of the target population at both the group and the individual level. The key here is that longitudinal studies extend beyond a single moment in time. As a result, they can establish sequences of events.

• To return to our example, we might choose to look at the change in cholesterol levels among women over 40 who walk daily for a period of 20 years.
• The longitudinal study design would account for cholesterol levels at the onset of a walking regime and as the walking behavior continued over time.

Therefore, a longitudinal study is more likely to suggest cause-and-effect relationships than a cross-sectional study by virtue of its scope.