epidemiology

  1. J

    EpiEstim package and discr_si function

    Hello everyone. I am working with the EpiEstim package (on R) in order to estimate "Rt" with incidence data. However, in the package documentation (https://cran.r-project.org/web/packages/EpiEstim/EpiEstim.pdf) there is a point that I can't properly understand. The function "discr_si" (which...
  2. P

    Should IRRs and HRs always be equal?

    I am running an analysis in a large population registry where individuals enter and leave the dataset at different time points. When i estimated the IRR between two distinct groups and a health outcome, and then a HR, I am finding a small difference (IRR 2.18, HR 2.01). Shouldn't they have...
  3. C

    Why is there a difference in the confidence intervals calculated by SPSS compared to SAS and Epi-Info 7?

    I writing sample code for colleagues in developing countries who will use it to analyze a multi-stage, cluster-sample survey that measures the prevalence of infection with soil-transmitted intestinal worms. So far, I have used three of the software packages they might use: IBM SPSS Statistics (I...
  4. C

    Can you include negative results when doing statistics of antibody titers?

    I need to analyse some antibody titers. Depending on factors they are divided into two (eg. male and female) or more groups. I have to compare the groups. Example: male 1/2 neg neg neg 1/8 female neg 1/4 1/16 1/2 1/4 For the descriptive part, if I got it right, I calculate the prevalence and use...
  5. P

    PAF through formula or through Conditional Logistic Regression

    Hi all, In a large registry dataset of psychiatric patients, if one wants to find the excess risk of schizophrenia patients developing depression, what would be the best method to apply: 1) Use the relevant formula to calculate PAF (Population Attributable Fraction). Formula can be...
  6. A

    Directed acyclic graph

    Hello I'm a beginner at epidemiology and have an assignment where I'm trying to create a DAG using dagitty to determine what to adjust for when looking at wether country of birth has an effect on general health. Besides the exposure (COB) and the outcome (GH) I have the following variables...
  7. M

    Measurement error in binary outcome variable for a case-control study

    I am currently working on a case-control study on a rare disease using a large patient database. Using conditional logistic regression I will calculate odds ratios for different exposures in cases and controls. The validity of the records for the disease of interest (outcome) is unknown. I...
  8. A

    How to analyze survey data with three levels of data in SAS?

    We analyze data from a European survey (34 countries ) for quality of life , the sampling procedure is described as a " multi-stage stratified and clustured sampling design " . Our outcome variable is binary. There are three levels of data to be taken into account (individuals, regions...
  9. K

    Need help with linear mixed modeling in SPSS

    So I've looked a quite a few tutorials and forums to see if anyone has posted something similar to the dataset I'm analyzing, and it doesn't seem like anyone has. I more need someone to tell me if what I'm doing is right or not. My data is looking at maternal cytokine levels during the...
  10. S

    How to become a statistician (Epidemiologist) If I have not measured in Statistics

    :yup: Hello There I am a masters student in health science. By health science I mean a mix of epidemiology, psychology, and health policy. It is a great major but I am leaning more toward epidemiology. But as you know It is not worth it to go back to school to get a MSc in Epi because there is...
  11. P

    detecting a variance trend in random effects

    Greetings I have a measurements on grouped individuals. There are approximately 100 groups, and approximately 500 individuals per group, with measurements taken over 5 years. There are no repeated measurements. The data are observational. The outcome is binary and there are 5 candidate...
  12. K

    Age as time scale

    I am generally a SAS user, I had a general question concerning how to fit survival models using age as the time scale within R. Would this fit be appropriate and also control for the left-truncated nature of the data? I know in SAS you need to specify a specific option. I was just...
  13. K

    Using Age as Time Scale

    I am generally a SAS user, I had a general question concerning how to fit survival models using age as the time scale within R. Would this fit be appropriate and also control for the left-truncated nature of the data? I know in SAS you need to specify a specific option. I was just...