Mean WAZ score and Prevalence <-2 SD by Measles Immunization

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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.

wpe1.jpg (13218 bytes)


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.

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