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Remember we started
out the day using gestation time as an example. Women who are malnourished risk have
premature babies, and studies are
being done to see whether different diet and vitamin supplements work
better. Let’s say the goal is to get them to carry the baby at least 240
days (8 months). For treatment 1, say
vitamins only, get normal distribution with mean 250, sd is 20.
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Treatment 2 is
vitamins plus a meals on wheels program. Mean is 266, sd 15 . You can eyeball
this and see that more of the women in treatment two are above our goal of
240 days, but how much of an improvement is it? The mean is increased, but the spread has
changed too. Let’s standardize to get
the proportion of women below 240 in each distribution.
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Go through - bottom
line is that adding food to vitamins resulted in the proportion of women with
gestation times of less than 240 days going from 30.85% to only 4.18%. You see figures like this in news stories
all the time - if you went to the primary (medical literature) you would see
that they had to go through this rigamarole to get you that tidy summary.
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