Scottish Surveys Core Questions 2024

5 Confidence Interval Calculations

All three source surveys are stratified to ensure sufficient sample sizes in smaller local authorities. SHeS is clustered in each annual fieldwork period - while this effect cancels out over each four-year period, it must be accounted for in producing annual results.

Confidence intervals have been calculated using a method to account for stratification, weights and clustering (surveyfreq in SAS/svymean in R). In the case of negative lower confidence interval limits, values were replaced by 0 as population percentages always range between 0% and 100%. Confidence intervals across all subgroup estimates in SSCQ are provided in the accompanying Supplementary Tables in the Supporting Documents section on the website.

Confidence intervals (at a 95% level) are displayed on point estimates for figures in the tables.

If the intervals surrounding two different point estimates do not overlap, then there is a significant difference between the two points. However, if they do overlap, it does not necessarily mean there is no significant difference (see further guidance).

A comparison of estimates of key variables across the three constituent surveys and the SSCQ are provided in Annex A.