Workforce attrition was calculated as psychiatrists ceased working because of factors such as retirement, ill health, or change of career.
Annual attrition is calculated by measuring the size of each cadre before new hires multiplied by the workforce attrition rates for each cadre.
A sample size of 192 participants (96 per study arm; alpha = 0.05, power = 90percent, 500 percent attrition) was calculated as being necessary to detect ECC incidence differences, based on reports of ECC incidence among Indigenous children in the literature (50 75 percent over two years).
Because there were only 9 years of data for specialists, meaning that attrition could be calculated for the first 5 years and then the next 3 years, the final 2 years of attrition for the second 5 year period was estimated on a pro rata basis from the attrition of the previous 3 years.
Longitudinal return and attrition rates were calculated (Table 2).
The attrition rate was calculated for all the drinking profiles in order to ascertain whether certain drinking profiles were associated with a greater or lesser degree of loss relative to the overall sample, For example, if heavy drinkers had a higher rate of loss, this might indicate that their non-participation at wave 5 was due to ill-health or death.
The information reported on attrition for the primary outcome was inconsistent across the trial reports, meaning that the rate of attrition could not be calculated confidently for many trials and so we did not attempt comparative analysis for this.
* There were no female psychiatrists aged 70 74 in 1995, thus attrition could not be calculated for this group.
Based on an anticipated reduction of 30% in the proportion of risky drinkers in control group and an overall attrition of 10%, it is calculated that 500 patients in each group will be needed to reject the null hypothesis (facilitated access is inferior to standard face-to-face intervention) with 90% power.
Attrition, mortality, and LTFU rates were calculated by summing the number of patients who experienced the event (attrition, death, or LTFU) during a particular period of time divided by the total number of years of follow-up during this period.
