How to recognize NURS study methodology

The difference between an observational study and an experimental study is whether or not the variable of interest in the study occurs naturally or outside of the researchers' control (observational) or if it was introduced intentionally and in a controlled way by the researchers (experimental).

Questions to Ask Yourself:

• Does the study look at the impact of a variable outside of the researchers' control? 
  • In observational studies, researchers look at data or make observations about a variable or intervention they are interested in, but do not actually control the distribution of. 
• Look at the methodology section. Does the study identify participants by looking through existing records or data?
  • Observational studies often choose participants because they are/were already reported to have a specific condition or because their medical records indicate they have received a specific intervention or treatment. 
• Is the article described in the title or methodology as:
  • Observational Study
  • Cohort Study
  • Case Control Study
• Would there be huge ethical issues if researchers controlled the intervention or variable of interest?
  • Observational studies often look at things that it would be unethical or impossible for researchers to distribute, cause, or selectively not distribute. Researchers cannot and should not for example expose participants to known diseases or harmful substances, impregnate participants, deny patients standard care, or change participants' identity or status around race, gender, sexuality, military involvement, ethnicity, disability, etc.

An example:

Researchers look at patients who were previously treated for skin cancer's medical records over twenty years compared to records of patients with no history of skin cancer to see if having skin cancer once makes it more likely that you will have it again.

The researchers (for obvious ethical reasons) can't give patients skin cancer to see if having it once makes it more likely to reoccur. 

Questions to Ask Yourself:

• Does the study look at the effects of a variable or intervention that the researchers intentionally introduce to a specific portion of the study participants?
  • In experimental studies, researchers deliberately introduce a variable or intervention to some study participants so they can judge its effects compared to those who never received that intervention or received a different intervention. 
• Does the methodology describe randomizing which participants are in the control group?
  • This is only possible in an experimental study because in an observational study the researchers have no control over who experiences the intervention or variable of interest. 
• Does the study control for other variables?
  • Experimental studies should be designed to account for other variables that may interfere with the results of the study. An example could be controlling the amount of time participants spend in direct sunlight when testing the effectiveness of different sunscreens. By controlling the amount of UV the participants are exposed to, any variation in the results is more likely due to the sunscreens used.
• Is the article described in the title or methodology as:
  • Randomized Controlled Trial
  • Controlled Trial
  • Clinical Trial
  • Experimental
  • Quality Improvement Project

An example:

Researchers split a group of patients who had all recently been treated for skin cancer into two groups. The control group received standard discharge care. The other group received standard care and attended a special "Sun Safety Class" to learn tips about using sunscreen, wearing protective clothing, and having regular screenings. Researchers then followed the two groups for twenty years to see if there was any difference in skin cancer recurrence between participants who received the "Sun Safety Class" intervention compared to participants who did not. 

The researchers here deliberately introduce a variable (the "Sun Safety Class") they control to some of the study participants. 

Questions to ask yourself:

• Does this study seem to have some elements of an experimental study?
  • Is there an intervention?
  • Is there a randomization of the independent variables?
  • Is there control over the independent variables?
• Does it lack any of the elements of an experimental study?
  • If some but not all of the elements of an experimental study are present, then the study is likely quasi-experimental.
• Does the study mention being quasi-experimental in the title, abstract, and/or methods sections?

An Example:

A group of researchers wanted to test the effectiveness of patient education to reduce vaccine hesitancy. They offered the class to all participants in the study, and those who were able to attend the session are the ones who received the intervention. Both groups were then asked about their thoughts on vaccines before, directly after, and one month after the class was offered. Since the intervention was not randomly assigned, and other variables were not taken into account, this study would be quasi-experimental.

The best place to search for Observational Studies is PubMed. This website makes searching for study types easy by providing filters you can use to limit your results. 

You can find this filter by:

1. Visit PubMed.
2. Type in your search. Leave out the study type from your search.
3. Find the filters section. This is typically on the left side of the screen or found by clicking Filters at the top of the search page.
4. Select See all article type filters, underneath the Article Type filter.
   1. If you don't see the Article Type option, select the Additional Filters button under the other filters.
5. Check the box next to Observational Study in the pop up window.
6. Then click on the blue Apply button.

This video shows goes over the basics of accessing PubMed and using it to filter for specific article types.