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Stata Problem Set

Econ 310

Due Tuesday, May 2nd, by 2:30 pm in class or on Canvas

Note: You must write or type your answers out on a separate sheet of paper and attach your Stata log. This assignment tests your ability to interpret the Stata output, so you cannot assume that we will understand your answer based solely on the raw Stata output. You may work on the problem  set with your classmates, but you must generate and include your own Stata log and write up your own answers, including graphs.

1.  Type the following command to load the lbw3 dataset (which is built into Stata): webuse lbw3 (or  use lbw3 on some older systems)

2.   Launch Stata and use the display command to write your name to the log. For

example, I would type the following command:

display "David Hansen"

3.   Use the describe command to determine which variable in this dataset contains maternal weight at last menstrual period (measured in pounds) and which variable contains infant birth weight. What units is infant birth weight measured in?

4.   Use the histogram command to graph a histogram of infant birth weight and to assess whether the distribution is symmetric or skewed. Does this distribution appear left-skewed, symmetric, or right-skewed?

5.   Use the summarize command with the detail option to calculate the mean, median, and standard deviation of infant birth weight.

6.   Use the ci command to calculate a 95% confidence interval for the population mean of infant birth weight. Interpret this confidence interval.

7.   Low birth weight is defined as being less than 2500 grams. Use the ttest command to test whether the population mean of infant birth weight is greater than 2500 grams using a 1% significance level. Make sure to write out the various components of the test, including your null and alternative hypotheses, your test statistic, and the result of your   test. What do you conclude?

8.   Use the sdtest command to test, using a 5% significance level, whether the population variance of infant birth weight is different for children of smokers and children

of nonsmokers. Make sure to write out the various components of the test, including your null and alternative hypotheses, your test statistic, and the result of your test. What do     you conclude?

9.   Use the ttest command to test (at a 5% significance level) whether the children of     mothers who smoke have a lower average birth weight. Make sure to write out the         various components of the test, including your null and alternative hypotheses, your test statistic, and the result of your test. What do you conclude?

10. Use the scatter command to graph a scatterplot of infant birth weight (on the y-axis) and maternal weight at last menstrual period (on the x-axis) and assess the relationship between the two variables. How strongly do they appear to be correlated?

11. Use the correlate command to calculate the correlation coefficient between infant birth weight and maternal weight at last menstrual period. Interpret the correlation between these variables. Why might the correlation go in this direction?

12.  Use the regress command to run a regression of infant birth weight and maternal weight at last menstrual period. Interpret R2 and the intercept and slope parameters from the regression model.