Hello,
I am struggling with ICC for 3 days.
Can anyone help me?
I am doing this research for my ophthalmology department.
Just to put you in context, measuring choroidal thickness has become an important tool for assessing its function and pathophysiology in many chorioretinal disorders.
However, there’s only one way to do it: manually. We have to find the upper and lower limits of the choroidal layer in a optical coherence tomography of the retina and measuring with a “rule” (a caliper built in the optical device)
Naturally, ophthalmologists think that this may be a subjective measurement, leading to variation between occasions in the same operator or with different operators.
We have made this study in my department: 2 different operators (an ophthalmologist and a resident in ophthalmology ) have measured the subfoveal choroidal thickness of nearly 80 eyes of 40 patients in two different occasions (with one month of interval). Of course the three of us were blinded for our own previous measurements and each other’s measurements.
I have to make the statistical analysis of the intraobserver variability and inter observer variability.
I am writing because I am confused about the statistical test I should use.
Many studies used intraclass correlation coefficient (CCC) and Bland-Altman plots. How can I do this using STATA? What model should I use?
one way, two way random effects or two way mixed model?
I read this in a blogue: to calculate an ICC in Stata Version 12.1 you will need your data in long format (ie. One column for the variable of interest, one column indicating which survey participant each row pertains to, and one column indicating which interviewer each row pertains to). Keep in mind that each survey participant is seen by a number of interviewers. The Intra-Class Correlation Coefficient is then calculated using Stata’s “icc” command.
I don't understand how I should change my columns...
Thank you all.
I am struggling with ICC for 3 days.
Can anyone help me?
I am doing this research for my ophthalmology department.
Just to put you in context, measuring choroidal thickness has become an important tool for assessing its function and pathophysiology in many chorioretinal disorders.
However, there’s only one way to do it: manually. We have to find the upper and lower limits of the choroidal layer in a optical coherence tomography of the retina and measuring with a “rule” (a caliper built in the optical device)
Naturally, ophthalmologists think that this may be a subjective measurement, leading to variation between occasions in the same operator or with different operators.
We have made this study in my department: 2 different operators (an ophthalmologist and a resident in ophthalmology ) have measured the subfoveal choroidal thickness of nearly 80 eyes of 40 patients in two different occasions (with one month of interval). Of course the three of us were blinded for our own previous measurements and each other’s measurements.
I have to make the statistical analysis of the intraobserver variability and inter observer variability.
I am writing because I am confused about the statistical test I should use.
Many studies used intraclass correlation coefficient (CCC) and Bland-Altman plots. How can I do this using STATA? What model should I use?
one way, two way random effects or two way mixed model?
I read this in a blogue: to calculate an ICC in Stata Version 12.1 you will need your data in long format (ie. One column for the variable of interest, one column indicating which survey participant each row pertains to, and one column indicating which interviewer each row pertains to). Keep in mind that each survey participant is seen by a number of interviewers. The Intra-Class Correlation Coefficient is then calculated using Stata’s “icc” command.
I don't understand how I should change my columns...
Thank you all.
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