I have looked in the SPSS algorithm PDF and unfortunately still need guidance for which specific equation matches our ICC analysis. In the ICC section of the algorithm PDF (IBM_SPSS_Statistics_Algorithms.pdf), they describe a type A average measure 2-way mixed ICC algorithm (pg. 963) and a type C average measure 2-way mixed ICC algorithm (pg. 964). I'm unsure which type matches our analysis and if the alpha reliability model, absolute agreement, and 95% confidence intervals are taken into account for either of these algorithms.
Secondly, does the type A and type C average measures 2-way mixed algorithms match the algorithms in McGraw and Wong 1996 (link to article below), Column effects fixed and row effects random (mixed effects model) in Table 5? This reference was cited in the SPSS algorithm PDF.
https://d1wqtxts1xzle7.cloudfront.net/25350178/mcgrawk1996a-libre.pdf?1390869144=&response-content-disposition=inline%3B+filename%3DForming_inferences_about_some_intraclass.pdf&Expires=1702577032&Signature=Mw1T7vbGi4pLNoAzRYEar3B5tdC7tGIvTsMxswnm2upkeG9Tlzzr~PgAaEgtMiTL~59bmo0vTMGBTwAagfpU-i1M~8AOtxNMUsY1CeOWpQFupkodz8sgChwqgcFASvhuesJ5fDp8oCLO9bpGe0RJg0TlBINmewdFwV9O~UqNX6dOHqFmLUJfyEWeuZ84AmulLHb8lnniwSHabzop9GlMpHbtvaWxv1F6i-e~xYN9byTsQw0zqlhBvXIzHouubTPLhdRChNfd8p04ebdpyKn8v0QjyX54Q3LMbnFE0lCLPbyi7opMieEziQRVpEGkOZkjy3Gj06ZfIvGBx-mXjf201g__&Key-Pair-Id=APKAJLOHF5GGSLRBV4ZA
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Lauren Pasetes
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Original Message:
Sent: Tue December 12, 2023 03:17 PM
From: Lauren Pasetes
Subject: Specific Equation SPSS uses for Intraclass Correlations
What is the exact formula/equation/calculation SPSS uses for this specific reliability analysis using intraclass correlation coefficients:
RELIABILITY
/SCALE('ALL VARIABLES') ALL
/MODEL=ALPHA
/ICC=MODEL(MIXED) TYPE(ABSOLUTE) CIN=95 TESTVAL=0.
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Lauren Pasetes
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