Statistical analysis
| Observed pattern in group B at 1, 4 and 6 months | Imputed value in group B at 1 month | Imputed value in group B at 4 month | Imputed value in group B at 6 months |
|---|---|---|---|
| mis*, mis, mis | X1-bar† | X4-bar‡ | X6-bar§ |
| mis, mis, Y3¶ | Y3—(δ1**+δ2††)‡‡ | Y3—δ2 | |
| mis, Y2, mis | Y2—δ1 | Y2+δ2 | |
| Y1, mis, mis | Y1+δ1 | Y1+δ1+δ2 | |
| Y1, Y2, mis | Y2+δ2 | ||
| Y1, mis, Y3 | (Y1+δ1+Y3—δ2)/2 | ||
| mis, Y2, Y3 | Y2—δ-1 |
Table to explain the use of imputing quantities derived from observed values in a group (group A) to impute missing values in a group (group B). mis, missing value, X1, value at month 1, X4, value at month 4, X6, value at month 6.
*The value at 4 months is missing in group B.
†Mean of values observed in group A at time 1 month.
‡Mean of values observed in group A at time 4 months.
§Mean of values observed in group A at time 6 months.
¶Observed value in group B at time 6 months.
**The mean of difference between values observed at time 4 months and value observed at time 1 month in group A.
††The mean of difference between value observed at time 6 months and value observed at time 4 months in group A.
‡‡If an imputed value is 0, it is set equal to 0.