smr using a reference population

[james cooper]

I will list what all have done so far
1- used the command contract year(2011-2021) postcode(1,2) agegroup(same range as reference pop)
2- and then merged my data using 1:1 merge with reference population to derive cases(cases in aggregate data i.e 3,6,2,1). missing data exists for agegroup with no cases(.)

Now the problem is i want to calculate the incidence rates, following the example on stata manual, it stated to have your standard population rates stored in a separate file. in this file, i have my reference agegroups and population(e.g agegroup 10-30, population=15395 in a sep .dta file)
MY QUESTION: in the example reference data used, they have ageband and rate(ageband 40, rate: 6.2), but i have ageband and population figure. Are they the same? basically im confused on what they used as rate, and how it was derived

[Clyde Schechter]

To compute a standardized mortality ratio you must have the mortality rates for the standard population and you must have population counts in your study population, both of them disaggregated into the same strata, which might be age groups, or sex and age groups, or some other scheme. Typically the data from the standard population and the data from the study population start out in different data sets and are brought together by -merge-ing them, though how you achieve a merge-d data set is incidental to the concept of smr.

Once you have all the combined data in memory, stratum by stratum you multiply the study population count by the standard population mortality rate to calculate the expected number of study population deaths in each stratum. Then you add those up to calculate an expected total number of deaths in the study population. You then divide that by the observed total number of deaths in the study population to get the standardized mortality ratio, which is often then multiplied by 100 to express it as a percentage.

If this description does not help you, it could be made more concrete if you posted back with an example of your data (preferably the merged data set, although a sample from each of the separate data sets that has the same strata in both would also do.

If you do that, please be sure to use the -dataex- command to show the example data. If you are running version 18, 17, 16 or a fully updated version 15.1 or 14.2, -dataex- is already part of your official Stata installation. If not, run -ssc install dataex- to get it. Either way, run -help dataex- to read the simple instructions for using it. -dataex- will save you time; it is easier and quicker than typing out tables. It includes complete information about aspects of the data that are often critical to answering your question but cannot be seen from tabular displays or screenshots. It also makes it possible for those who want to help you to create a faithful representation of your example to try out their code, which in turn makes it more likely that their answer will actually work in your data.