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Table 1 A summary of the advantages and disadvantage of distribution, anchor and qualitative methods

From: Defining the minimally clinically important difference of the SF-36 physical function subscale for paediatric CFS/ME: triangulation using three different methods

  Advantages Disadvantages
Distribution method • Distribution methods are based on statistical models [3].
• The value of 0.5 SD corresponds to the MCID across a variety of studies [4].
• Guidelines for the interpretation of effect size are somewhat arbitrary.
• This statistical approach does not consider the core concept of the MCID; the clinical importance [8].
• These methods are sample-specific; findings will vary on the sample size and distribution that the SD is based on [38].
Anchor method • Anchor methods have the advantage of being more clearly understood because change scores are related to a clearly understood clinical observation [39].
• Global assessment scales are sensitive to change [40].
• Determining the cut-off on the anchor scale is often an arbitrary decision [7].
• Global assessment scales may not always be valid. For example, they can be susceptible to recall bias [41].
Qualitative methods • Gathering the views and experiences of patients provides clinical relevance to the MCID.
• Qualitative data provides richer information from the participants perspective which cannot be elicited through standardized measures [8].
• Can lack the precision needed to determine a numerical marker of MCID [8].
• Often includes smaller sample sizes, which can introduce issues with generalisability [42].