Type II error
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Type II errors (beta errors, β) occur when we accept that there is no difference between two experimental groups, when in fact, there is a difference.
The p-value does not give a direct indication of the likelihood of a type II error; if the p-value is >0.05, this does not necessarily mean that the two experimental groups are similar. This would only be true if the study is powered to a size to detect a difference if it were present 2.
By convention, we try to keep β = 0.15-0.20
Factors that affect the β:
- the size of the difference between the groups
- variability within groups
- the likelihood of committing a type I error
- sample size: the larger study, the more power and the less likelihood of a β error
-<p><strong>Type II errors</strong> (<strong>beta errors, β</strong>) occur when we accept that there is no difference between two experimental groups, when in fact, there is a difference.</p><p>The <a href="/articles/p-value">p-value</a> does not give a direct indication of the likelihood of a type II error; if the p-value is >0.05, this does not necessarily mean that the two experimental groups are similar. This would only be true if the study is <a href="/articles/power">powered</a> to a size to detect a difference if it were present <sup>2</sup>.</p><p>By convention, we try to keep β = 0.15-0.20</p><p>Factors that affect the β:</p><ul>- +<p><strong>Type II errors</strong> (<strong>beta errors, β</strong>) occur when we accept that there is no difference between two experimental groups, when in fact, there is a difference.</p><p>The <a href="/articles/p-value-1">p-value</a> does not give a direct indication of the likelihood of a type II error; if the p-value is >0.05, this does not necessarily mean that the two experimental groups are similar. This would only be true if the study is <a href="/articles/power">powered</a> to a size to detect a difference if it were present <sup>2</sup>.</p><p>By convention, we try to keep β = 0.15-0.20</p><p>Factors that affect the β:</p><ul>
References changed:
- 3. Trout AT, Kaufmann TJ, Kallmes DF. No significant difference . Says who?. AJNR Am J Neuroradiol. 2007;28 (2): 195-7. <a href="http://www.ncbi.nlm.nih.gov/pubmed/17296976">Pubmed citation</a><span class="auto"></span>
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