cancel
Turn on suggestions
Auto-suggest helps you quickly narrow down your search results by suggesting possible matches as you type.
Showing results for 
Search instead for 
Did you mean: 
iuri_leite
‎10-08-2024
  • 47 Posts
  • 1 Likes Given
  • 0 Solutions
  • 0 Likes Received

95% confidence interval for incidence rate

by Fluorite | Level 6 in Statistical Procedures
‎01-05-2022 10:26 AM
‎01-05-2022 10:26 AM
Dear all,   I am still struggling to estimate 95% confidence interval for a data set in which we did not observe the event.  I have a dummy variable that indicates the event occurrence  and the number of person-years. I did not observe nay event and the number of person-years is equal to 116.42. Then, the incidence rate is zero (0/116.42). But I would like to estimate the confidence interval. I used Proc Genmod and it gives me a perfect result when events occurred. Whithout events I do not get the confidence intervals.It would be possible to estimate the confidence interval?   Regards,   Iuri ... View more

Re: Confience interval when the incidence is zero

by Fluorite | Level 6 in Statistical Procedures
‎01-03-2022 07:12 PM
‎01-03-2022 07:12 PM
Dear Dave, Yes. we did not observe any event and the total number of person-years was 116.42. Then the incidence was 0/116.42=0. My problem is to estimate the confidence interval. Thanks again. Regards, Iuri ... View more

Re: Confience interval when the incidence is zero

by Fluorite | Level 6 in Statistical Procedures
‎01-03-2022 04:01 PM
‎01-03-2022 04:01 PM
Dear Dave,   Yes. we did not observe any event and the total number of person-years was 116.42. Then the incidence was 0/116.42=0.   My problem is to estimate the confidence interval.   Thanks again.   Regards,   Iuri ... View more

Re: Confience interval when the incidence is zero

by Fluorite | Level 6 in Statistical Procedures
‎01-03-2022 12:48 PM
‎01-03-2022 12:48 PM
Dear Dave,   thanks for sending me the code.   I used it, but i am not sure about the result I obtained.   As I told you, I am analyzing the incidence of HIV among participants of cohort. So, I have a binary variable indicating the participant seroconverted  (1) or not (0). I have also the follow-up time of each participant in the cohort. Then I estimated the incidence for a set of characteristics. For some characteristics I did not observe any event;  the incidence is zero. I would like to obtain the confidence interval. I used the syntax you send me:   proc genmod; model soroconversao = / dist=poisson offset=log_ano; exact intercept / estimate=both; run;   The SAS output was:       The GENMOD Procedure   Exact Conditional Analysis Exact Conditional TestsEffect Test Statistic p-ValueExact MidIntercept Score  Probability 122.0 <.0001 <.0001 2.35E-42 <.0001 <.0001   Exact Parameter EstimatesParameter Estimate   StandardError 95% Confidence Limits p-ValueIntercept -0.3144 * . -Infinity . <.0001 Note: * indicates a median unbiased estimate and a one-sided p-value.     Exponentiated Exact Parameter EstimatesParameter Estimate   95% Confidence Limits p-ValueIntercept 0.7302 * 0 . <.0001 Note: * indicates a median unbiased estimate and a one-sided p-value.   I would like to know whether the value 0.7302 is the upper limit of the interval. It is not clear to me. Thanks a lot. regards, Iuri           ... View more

Re: Confience interval when the incidence is zero

by Fluorite | Level 6 in Statistical Procedures
‎12-30-2021 06:28 PM
‎12-30-2021 06:28 PM
Dear Koen, I used Proc Genmod: proc genmod; model soroconversao = / dist=poisson offset=log_ano; estimate "log(rate)" intercept 1; run; Soroconversao is a binary variable indicating that the person is a case or not (1 or 0); log_ano is the log of the person-years; Thanks a lot. Regards, Iuri Leite ... View more

Confience interval when the incidence is zero

by Fluorite | Level 6 in Statistical Procedures
‎12-30-2021 04:57 PM
‎12-30-2021 04:57 PM
Dear All,   I estimated incidence according to demographic characteristics of a population. For some characteristics  we did not observe any case, then the incidence was zero. I used a Poisson Regression and in these cases SAS did not reported the confidence intervals. In fact, if I calculate it, the intervals varies from 0 (zero) to +infinity.  Then, I would like to know how to report the incidence in those cases.   Thank you in advance. Regards,   Iuri Leite ... View more

Re: Sampling design

by Fluorite | Level 6 in Statistical Procedures
‎08-09-2021 08:22 AM
‎08-09-2021 08:22 AM
Dear Reeza, thanks a lot. Regards, Iuri ... View more

Sampling design

by Fluorite | Level 6 in Statistical Procedures
‎08-06-2021 11:40 AM
‎08-06-2021 11:40 AM
Dear Colleagues,   I am studying to calculate the sample size of a study. We have two treatment (A and B) and we know that in a randomized study treatment A was more effective than treatment B. In the study proposed we will offer the two treatments to the participants and they will have to choose between them. We believe that 75% will choose the treatment A. In the study the participants will be able to change the treatment once. They will be followed up for at least one-year and we are interested in looking various outcomes with one of them being adherence to treatment.   Then I would like to know if anyone could give me some ideas and references. I've never read anything on sample size in which the participant choose the treatment a may change the treatment.   Thank you in advance, Regards, Iuri   ... View more

Re: Nested Models

by Fluorite | Level 6 in Statistical Procedures
‎02-18-2021 05:54 PM
‎02-18-2021 05:54 PM
Sorry to bother you again. My point is that in the Hosmer and Lemeshow book, they use the likelihood ratio test in a very similar way. I found it strange. They aggregate the four categories of a variable into two new categories. And then they compared the two models using the log-likelihood ratio test. Regards ... View more

Re: Nested Models

by Fluorite | Level 6 in Statistical Procedures
‎02-18-2021 05:20 PM
‎02-18-2021 05:20 PM
Thanks for the answer. In fact, it is clear to me that it is not nested. What I do not uderstand is the use of the log-likelihood ratio test should it onlly be used for nested models? Thanks again. Regards? Iuri ... View more

Nested Models

by Fluorite | Level 6 in Statistical Procedures
‎02-18-2021 03:13 PM
‎02-18-2021 03:13 PM
Dear All, I have a simple question that I do not know to define precisely. Suppose I run a logistic regression with a explanatory ordinal variable with for categories, with the first category as refference. Then I agregated the first category with the second (0) and the third with the fouth (1), so that I have now a dummy variable. I run another model. Why is that model a nested one? If it is nested, how do I define what is being tested. I had B1, B2 and B3 as parameter. Now I have one B measures the effect of the third and fourth category compared to the agregation of the two first categories. Thank you in advance. Best regards, Iuri   ... View more

Random effect statistical significance Proc Glimmix

by Fluorite | Level 6 in Statistical Procedures
‎08-19-2020 12:22 PM
‎08-19-2020 12:22 PM
Dear fellows,    I am using Proc Glimmix with a longitudinal data in which the event is observed at week 0, 48 and 96. I am using a logistic regression and I would like to test whether the random effect is significant as the sas output show only the parameter estimate and its respective standard  . Is it done with COVTEST?   The  Syntax used is:   proc glimmix data=t6 method=quad; class pid1; model GONOR= /dist=bin link=logit s; random int / subject=pid1 type=ar(1); RUN;   Thank you in advance. Best regards, Iuri Leite       ... View more

Re: Proc Glimmix

by Fluorite | Level 6 in Statistical Procedures
‎07-03-2020 05:13 PM
‎07-03-2020 05:13 PM
Dear Paige Miller,   thanks a lot.   Best regards,   Iuri  ... View more

Re: Ordinal Logistic with random effects

by Fluorite | Level 6 in Statistical Procedures
‎07-02-2020 10:15 AM
‎07-02-2020 10:15 AM
Dear Steve,   thanks a lot.   Best regards, Iuri ... View more

Re: Ordinal Logistic with random effects

by Fluorite | Level 6 in Statistical Procedures
‎07-02-2020 10:14 AM
‎07-02-2020 10:14 AM
Dear Steve, many thanks. If I have any problem I will come back with the codes and errors. Best wishes, Iuri ... View more
Contact Me
Online Status
Offline
Date Last Visited
‎10-08-2024 04:36 PM
Likes given to
View All
Quick links