Mean WAZ score and Prevalence <-2 SD by Measles Immunization
Exercise in Running the Mean Outcome scores:
1. Open keast4j.sav
2. Click on Statistics, Compare Means, Means and enter waz (weight for age z-score) and waprev (weight for age prevalence <-2 SD) in the Dependent Variable list using the arrow key.
3. Enter the variable hmeasyn (yes/no for measles immunization) into the Independent Variable box.
4. Click on OK.
INTERPRETATION:
The outcome is shown so the mean WAZ score can be compared between the immunized and non-immunized group. There is a higher z-score (better nutritional status overall) for those children who have not been immunized (-0.916 compared to -1.429). This corresponds to the outcome for prevalence, where the numbers should be multiplied by 100 to give the percentage. There are only 22% under -2 SD for those not immunized, but 33% under -2 SD for those that did get immunized. This could seem perplexing, since one would think that immunizing a child would have a protective, not a harmful effect. Think about this for a bit. Don't just believe what you see until you look further.