You need to decide if your research project will take a EXPERIMENTAL, CROSS-SECTIONAL or LONGITUDINAL research design approach.
Experimental Research Design
An experimental research design is basically a research that performs an experiment or test of some sort, for example an experiment that tests whether an energy drink improves aerobic running performance.
The experiment usually involves testing whether a dependent variable affects an independent variable. The dependent variable is what is being tested, for example performance. The independent variable is the thing you are trying to see if it effects the dependent variable, for example energy drink.
The experiment normally involves a treatment group and a control group, but not always, it depends on the experiment! The treatment group are the group of participants who are given the independent variable, for example they take the energy drink. The control group are the group of participants who are still tested but do not take the independent variable, for example do not have an energy drink but still do the running test. The tester can then compare the treatment group to the control group and see if the independent variable (energy drink) made a difference.
The experiment will most likely contain a repeat test. This simply involves the treatment group being tested on the dependent variable, for example a timed 5km run. The treatment group then take / experience the independent variable, for example drink 200ml of energy drink. The treatment group then repeat the test, for example timed run of 5km again. The control group do two 5km runs (with a rest between). The researcher can then see if the treatment group’s energy drink run is better than their first and the control group’s runs.
If the treatment group’s energy drink run is quicker than their no energy drink run and the two control group’s runs, then the energy must have influenced and improved performance! The independent variable influenced the dependent variable!
Cross-Sectional Research Design
A cross-sectional research design is a research that looks at and compares different variables at the same time. The variables could be different types of people, for example different genders, races, ages, incomes etc. Another set of variables could be different businesses, geographical areas, sports etc. For example, a research comparing the types of people and the sports they play, the results might show whether a particular race or income group play different sports to another race or income group. For example, maybe the results show that white, 30-40-year-old males who earn under £30,000 a year play different sports to black, 30-40-year-old males who earn over £30,000 a year.
A cross-sectional research design could consist of asking a diverse group people or businesses etc about their life, habits or routines through a survey, then with the collected results look for difference and similarities in their responses. It could be that you ask different people to undertake a test or take a supplement, then again look for difference and similarities in their scores or reactions. Or it could comprise of you looking at previously collected data (secondary data) and look for differences and similarities between the different types of people, business, job, geographical areas.
Longitudinal Research Design
A longitudinal research design is a study that is completed over an extended period of time, it could be decades. The research would study a particular topic, area, aspect etc for a long period of time. The aim of the research design is to see changes over time. For example, a study could look at the changes in sport participation over the last 50 years. This is very timely and costly because you would have to collect data and results for many years to complete the research.
A longitudinal research could comprise of following the same people for a long period of time. For example, you could ask a set of 20-year-old participants how any hours of sport they play a week, then ask them again at 25 years old, again at 30, 35, 40 etc. You would then look to see the changes over time.
Another example could be asking a set of individuals whether they smoke, drink alcohol etc, then follow their health for the next 40 years. The research would then look for trends in good health and poor health, for example the smoker participants have more poor health than the non-smokers.