Parameters:
(1) number of features that potentially can be matched
(2) number of features not visible on the different sets of films
(3) number of features that match or align
concordance =
= (number of features that match) / ((number of potential features) – (number of features not visible between the sets of films)) * 100%
Interpretation:
• minimum score 0
• maximum score 100%
• The higher the score the greater the match.
• Wood et al used >= 80% as evidence for a match in their study of dental findings.
Expanding upon this, I have come up with the following as a tentative scheme.
|
Concordance
|
Match
|
|
100%
|
perfect
|
|
90 – 99%
|
close match
|
|
80 – 89%
|
match
|
|
20 – 79%
|
partial match
|
|
< 20%
|
no match
|
Limitations:
• There needs to be a minimum number of features available for comparison (potential number minus the available number). The higher the number the greater the confidence there would be in the interpretation. The Student's t-rest can be used to give the true significance for each case.
• Comparison of radiographs would only be valid if the feature being studies was likely to be stable over the intervening period,
