Age and sex standardised incidence rates If I were to compute age-sex standardised incidence rates based on a simple random sample of a nationwide household survey on hearing loss. Noting that this a sample not the total population, so the denominator is known (The total number of people residing within the country is known by age and sex) however the numerator is known for both age and sex, but is only a sample. Would this be valid?
When we were taught Epidemiology, we knew and were given examples of incidence rates based on entire populations or disease registries (The numerator was not a sample, but was a count of all actual cases). What about a huge sample of people in the tens of thousands?
Thank you
Sarah

Yes, one can use randomised sampling/surveys to calculate rates stratified by other factors such as age and sex. Often, simple random sampling is not ideal when one is interested in subgroups, especially when some of those subgroups are rare. If an ethnic group you are interested in is just ~0.1% of the population, there may not be a single individual from this group sampled if the sampling was totally random. Stratified sampling is a good way to deal with this. If one has to deal with data that is already collected in a simple unstratified manner, 'poststratification' can be very helpful.
I have added tags to your question that will point you to further threads on these topics.
