Dear Allstat members,
I would be grateful if you could please advise me as to which
reliability statistics I should use in this case. My colleagues are
interested in assessing the agreement between two readers who each
assessed patients' MRI scans for the number of certain abnormalities
present. For each patient I therefore have two abnormality counts, one
from each reader. Because these are counts, Kappa-like statistics are
not applicable since there are no defined categories into which each
reader places each patient. I was initially drawn towards Intraclass
Correlation Coefficients, but strictly speaking I don't think ICCs are
suitable for count data either since they are ANOVA-based (please
correct me if I'm wrong in assuming this). The majority of patients have
no abnormalities, which serves the dual purpose of skewing the data into
significant non-normality, whilst making it difficult to perform
transformations (given that most of the data points are zero). Any hints
on how best to proceed here would be greatly appreciated.
Thanks in advance,
Liz Hensor
Dr Elizabeth M A Hensor PhD
Data Analyst
Academic Unit of Musculoskeletal and Rehabilitation Medicine
36 Clarendon Road
Leeds
West Yorkshire
LS2 9NZ
Tel: +44 (0) 113 3434944
Fax: +44 (0) 113 2430366
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