{"action":"opened","issue":{"url":"https://api.github.com/repos/simsem/semTools/issues/48","repository_url":"https://api.github.com/repos/simsem/semTools","labels_url":"https://api.github.com/repos/simsem/semTools/issues/48/labels{/name}","comments_url":"https://api.github.com/repos/simsem/semTools/issues/48/comments","events_url":"https://api.github.com/repos/simsem/semTools/issues/48/events","html_url":"https://github.com/simsem/semTools/issues/48","id":382874886,"node_id":"MDU6SXNzdWUzODI4NzQ4ODY=","number":48,"title":"semTools reliability vs. psych omegaFromSem","user":{"login":"daveflora","id":45215894,"node_id":"MDQ6VXNlcjQ1MjE1ODk0","avatar_url":"https://avatars0.githubusercontent.com/u/45215894?v=4","gravatar_id":"","url":"https://api.github.com/users/daveflora","html_url":"https://github.com/daveflora","followers_url":"https://api.github.com/users/daveflora/followers","following_url":"https://api.github.com/users/daveflora/following{/other_user}","gists_url":"https://api.github.com/users/daveflora/gists{/gist_id}","starred_url":"https://api.github.com/users/daveflora/starred{/owner}{/repo}","subscriptions_url":"https://api.github.com/users/daveflora/subscriptions","organizations_url":"https://api.github.com/users/daveflora/orgs","repos_url":"https://api.github.com/users/daveflora/repos","events_url":"https://api.github.com/users/daveflora/events{/privacy}","received_events_url":"https://api.github.com/users/daveflora/received_events","type":"User","site_admin":false},"labels":[],"state":"open","locked":false,"assignee":null,"assignees":[],"milestone":null,"comments":0,"created_at":"2018-11-20T22:30:28Z","updated_at":"2018-11-20T22:30:28Z","closed_at":null,"author_association":"NONE","body":"hi guys,\r\nWhen I fit a one-factor model in lavaan, with no error covariances, I can calculate omega \"by hand\" with\r\nparam <- lavInspect(lavfit, \"est\")\r\nfitted <- lavInspect(lavfit, \"cov.ov\")\r\nnum <- sum(param$lambda)^2\r\nden <- sum(num + sum(param$theta))\r\nden2 <- sum(fitted)\r\nmyOmega <- num/den\r\nmyOmega2 <- num/den2\r\n\r\nFor the data set I'm using, both of these calculations give me approximately (within .01) the same result as\r\nlibrary(psych)\r\nomegaFromSem(lavfit)\r\n\r\nSpecifically, for my data I get around .78 or .79 for omega from the calculations above. If I use the observed covariances in the denominator, I get omega = .81.\r\n\r\nBut when I run\r\nreliability(lavfit)\r\n, the 3 omega estimates are all much lower, around .64.\r\nI've been banging my head on the semTools documentation, trying to figure out how the formulas might be different, but I can't figure it out. Does it have something to do with the residual correlations?\r\n\r\nthanks,\r\nDave"}}
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