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Introduction

Part 2.
Search: Efficiently search for research evidence.

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How can I find the best evidence in five minutes or less?

(Estimated time: 1 hour)

Using the question you framed in Part 1:

What is the effectiveness of non-legislative interventions to promote the use of bike helmets, compared to provincial legislation alone, on the use of cycling helmets among children aged 4 to12?

How would you begin a search to get yourself the best evidence?

As mentioned in Part 1, just searching PubMed on helmets yielded over 2 600 hits. One of the downsides of the information age is clearly information overload!

A proposed hierarchy of quantitative evidence indicates that some study designs are considered stronger - that is, more free of bias - than others. The top of the hierarchy of quantitative evidence is where you find the strongest evidence for a question about intervention effectiveness. No study of people, designed by people, could ever be totally free of bias but, as you go down the hierarchy, the likelihood of bias is greater. The use of this hierarchy has led to one of the unfortunate myths of evidence-informed decision making: that only systematic reviews or randomized controlled trials can be considered evidence. In reality, all study designs are forms of research evidence. When you are making a decision about instituting a change in practice or policy, however, you would want to use the research evidence from the highest point in the hierarchy that you could find. For some questions, that may very well be case control studies, or expert opinion!

Hierarchy of quantitative evidence

cautionIt is very important to note that this hierarchy does NOT include qualitative research. Qualitative research answers questions about experience or meaning.

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