Survey

Survey

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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? Page 1 of 1

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