Table 3 Sample size calculation (https://select-statistics.co.uk/calculators/sample-size-calculator-two-proportions/)
From: Routine developmental screening in Australian general practice: a pilot study
Based on an expected documentation of developmental status at a rate of 10% at baseline (in line with a baseline rate obtained in a previous study [17]) and aiming to double this to 20% following |
the intervention [17], required a minimum sample of 197 records in each sample (given 95% confidence level and 80% power). Adding a 20% buffer |
on this number (to allow for attrition by removing of duplicates) equates to 246 records, rounded to 250 per sample |