Sentence examples for for both case and control periods from inspiring English sources
We then reran this same model, replacing the 24-hr mean PM2.5 concentration (for both case and control periods) with one of six lagged mean PM2.5 concentrations (i.e., mean of hours 24 47, 48 71, 72 95, 96 119, 120 143, or 144 167 before ED arrival) to estimate the risk of MI associated with each lagged PM2.5 concentration.
A one-year period prevalence was calculated for each co-morbidity for both case and control groups.
We selected an interval of 2 weeks between case and control periods to minimize autocorrelation between case and control exposures and to control for seasonal effects.
Therefore, the observation period for both cases and controls was the period between the date of entry into the CPRD and the index date.
The average age at diagnosis for cases was 63 years, and both cases and controls lived at 4.8 addresses, on average, during the period 1971 2003.
About half of both cases and controls used oral contraceptives in the past, but the cases used them for a longer period of time than the controls (median: 10 years and 4.5 years, respectively; p-value 0.018).
Control periods were chosen 4 weeks before or after the index event to effectively control for temporal trends but without overlap between the case and control exposure periods.
Milk replacers were fed to calves during a relatively short period after birth (an average of 79 and 68 days, for case and control farms, respectively).
However, usage was similar for cases and controls in time periods more distant from index dates.
Control periods most frequently used for the symmetric design are 7 days before and after case, and for the time-stratified design, control periods are all the same days of the week as the case within the same month.
The analysis was also carried out for the control daily activity areas for each of the four annual periods to highlight differences in the location and characteristics of high overlap areas for cases and controls, over the four year period.
