Topic 11B: Hierarchies of Evidence


These are the solutions for the Topic 11B Computer Lab.

1 Introduction to hierarchies of evidence

1.1

  1. Systematic reviews and meta analyses: From the question sheet: A systematic review is where a collection of studies on the same or a related topic are gathered, and their results are reviewed and analysed. As part of this systematic review, a meta analysis may be carried out. This involves combining the statistical results of the individual studies to estimate an overall effect.
  2. Randomised controlled trials are studies where participants are randomly allocated to different groups.
  3. Cohort studies: this is where two or more cohorts are identified based on their exposure to certain elements. They are then followed up at a later date to see whether a particular outcome has eventuated
  4. Case-control studies: subjects with a particular condition are “matched” to similar subjects without the condition. Comparison between groups can then be made.
  5. Cross sectional surveys: a group of individuals complete a survey. The individuals may naturally already belong to different groups, but individuals are not randomly allocated to groups.
  6. Case reports: A story (or perhaps set of stories) is told about one (or more) subject. While inferential evidence is not strong due to the very small sample, the level of detail about the subject and depth of insight may be greater here than in a larger study.
  7. Expert opinion: This is somewhat self-explanatory: it involves an expert providing their opinion on a particular topic or issue. This does not involve a formal study, which is why it is considered the weakest of the seven types of evidence.

2 Evaluating studies

2.1

At best, this may be considered a cross sectional study. However, the article was not peer-reviewed, where it would have been subjected to scrutiny over whether or not the research methodology was rigorous. Therefore, it falls into the category of expert opinion.

2.2

This was a cross sectional survey.

2.3

Randomised controlled trial.

2.4

Meta analysis.

References


These notes have been prepared by Amanda Shaker. The copyright for the material in these notes resides with the authors named above, with the Department of Mathematics and Statistics and with La Trobe University. Copyright in this work is vested in La Trobe University including all La Trobe University branding and naming. Unless otherwise stated, material within this work is licensed under a Creative Commons Attribution-Non Commercial-Non Derivatives License BY-NC-ND.