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Name __________________________
Date_______________
Please turn in at the end of lab.
II. Exercises
1. Opening STATA dataset, checking and describing dataset.
Using lowbwt from: http://www.stat.brown.edu/Zwu/PHP2500.aspx
Save this file into your temp directory and open in STATA.
a. How many observations are in this dataset?
b. How many variables are in this dataset?
c. Using the information from describe and from the data browser please identify the type of
each variable:
sbp:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
sex:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
tox:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
grmhem:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
gestage:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
apgar5:
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
d. Generally apgar scores 3 or below are considered critical, scores 4-6 are considered low and
scores 7+ are considered normal. Please create a new variable named status with the values
1=critical, 2=low and 3=normal.
What type of variable is status?
nominal categorical
ordinal categorical
continuous numeric
discrete numeric
2. Summarize variables
a. What percent of babies are considered “critical” according to the apgar5 score?
b. What percent of babies are considered “normal” according to the apgar5 score?
c. What is the mean systolic blood pressure?
d. What is the median systolic blood pressure?
e. What is the 90% centile of systolic blood pressure?
f. What is the range for systolic blood pressure?
g. What is the interquartile range (Q3-Q1)?
h. What is the variance?
i. What is the standard deviation?
j. 25% of observations have a systolic blood pressure below _______.
i. What is the mean systolic blood pressure for babies with a diagnosis of germinal matrix
hemorrhage? (hint: use “summarize by”, review the example of age summary by smoking
status)
j. What is the mean systolic blood pressure for babies without a diagnosis of germinal matrix
hemorrhage?
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