HEALTH AND NUTRITION SURVEY (HANES)
In the years 1976 – 80 the Public Health Service examined a representative cross-section
of 20,322 Americans age 1 to 74 in the Health and Nutrition Survey (HANES).
The objective was to get data about demographic variables (age, education, income),
physiological variables (height, weight, blood pressure), dietary habits, and other
variables.
1. The figure at the bottom [see page 59] shows average heights and weights
separately for the men and the women. The average height seems to decrease after
age 20, dropping about two inches in 50 years. Should you conclude that an
average person will get shorter at this rate? Discuss.
There were 6,588 women age 18 – 74 in the HANES sample. Their average height was
63.5 inches, and the standard deviation (SD) was 2.5 inches.
A value is converted to standard units by seeing how many SDs it is above or below the
average.
2. One of the women is 68.5 inch tall. Is she above or below average? By how many
SDs? What is her height in standard units?
3. Convert the following heights to standard units: 66 inches, 58.5 inches, 64 inches,
63.5 inches.
4. Find the height which is –1.2 in standard units.
FINDING AREAS UNDER THE NORMAL CURVE
5. Find the following areas under the normal curve:
a.
b.
c.
d.
e.
f.
g.
h.
between –1.2 and 1.2
between 0 and 1.65
between 0 and 3.3
between –0.35 and 0.95
between –2.1 and –1.05
between 1.2 and 1.85
to the right of 1
to the left of 0.85
6. The heights of the men age 18 – 74 in the HANES sample averaged 69 inches; the
SD was 3 inches. Use the normal curve to estimate the percentage of the men with
heights between 63 inches and 72 inches.
7. The heights of the women age 18 – 74 in the HANES sample averaged 63.5
inches; the SD was 2.5 inches. Use the normal curve to estimate the percentage of
heights above 60 inches.