I am looking for a SAS program to implement the regression based direct standardization of rates as described in the following paper. https://bmchealthservres.biomedcentral.com/articles/10.1186/1472-6963-8-275 ... View more

Hi, I am trying to obtain adjusted rate with 95% CI from a Poisson model for each cluster in the dataset. Please see the attached dataset. I am fitting the following GEE model. I am also happy to consider a random effects model if that helps. PROC GENMOD data=ForIndQ.sample_data; CLASS x1 cid; MODEL y=x1-x4 /d=poisson link=log offset=log_offset; REPEATED subject=cid/ type=exch; RUN; Here CID is the cluster id and I want to get the adjusted rates from the model with 95% CI for each of the CID. ... View more

Can you please help me with sample size calculation of a clustered RCT where the outcome is a rate and there is a baseline rate? That is at the beginning of the study both groups will have an outcome rate of 76/1000 days. We will have 23 clusters in each arm and 104 participants per cluster (SD=33) and expecting to follow-up the groups for 1 years. We need to know the minimum detectable difference for 80% power at 5% level with an ICC of 0.01. I am using the following Stata command but the effect size looks very high. clustersampsi, rates detectabledifference r1(.076) m(37960) k(23) rho(.01) size_cv(.45) alpha(0.05) beta(0.8) base_correl(0)   when I am doing the calculation for a stepped wedged RCT with 3 steps (3 months duration) it is coming much lower. steppedwedge, rates detectabledifference complete(1) vartotal(1) r1(.076) m(9360) k(12) rho(.01) alpha(0.05) beta(0.8) steps(3)   The difference is very high. I want to cross-check this with a SAS program. ... View more

Can you please help me with sample size calculation of a clustered RCT where the outcome is a rate and there is a baseline rate? That is at the beginning of the study both groups will have an outcome rate of 76/1000 days. We will have 23 clusters in each arm and 104 participants per cluster (SD=33) and expecting to follow-up the groups for 1 years. We need to know the minimum detectable difference for 80% power at 5% level with an ICC of 0.01. I am using the following Stata command but the effect size looks very high. clustersampsi, rates detectabledifference r1(.076) m(37960) k(23) rho(.01) size_cv(.45) alpha(0.05) beta(0.8) base_correl(0)   when I am doing the calculation for a stepped wedged RCT with 3 steps (3 months duration) it is coming much lower. steppedwedge, rates detectabledifference complete(1) vartotal(1) r1(.076) m(9360) k(12) rho(.01) alpha(0.05) beta(0.8) steps(3)   The difference is very high. I want to cross-check this with a SAS program.   ... View more

Hi, Can we calculate minimum detectable effect size for a cluster randomise trial(cRCT)? I have the following situation. A two arm cRCT with 20 clusters in each arm, average cluster size is 30 (SD=20). Power=80%, Alpha=0.05. Proportion of outcome in the control group is 65%. What difference in the outcome between the 2 arms I can estimate from this study? Bayzid ... View more

Is there any easy way to calculate sample size for a Poisson model with offset? I am planning a cohort study with recurrence short term outcome. That is, one participant can get the outcome multiple times during the follow-up period. ... View more