Introduction to Econometrics
Exercises - week # 1
All exercises are based on A.H. Studenmund, Using Econometrics: A Practical Guide.
1. A researcher is analyzing data on the financial wealth of 100 professors at a small
liberal arts college. The values of their wealth range from $400 to $400,000, with
a mean of $40,000, and a median of $25,000. However, when entering these data
into a statistics software package, the researcher mistakenly enters $4,000,000 for the
person with $400,000 wealth. How much does this error affect the mean and median?
2. Which has a higher expected value and which has a higher standard deviation: a
standard six-sided die or a four-sided die with the numbers 1 through 4 printed on
the sides? Explain your reasoning, without doing any calculations, then verify, doing
the calculations.
3. The heights of U.S. females between age 25 and 34 are approximately normally
distributed with a mean of 66 inches and a standard deviation of 2.5 inches. What
fraction of U.S. female population in this age bracket is taller than 70 inches, the
height of average adult U.S. male of this age?
4. A woman wrote to Dear Abby, saying that she had been pregnant for 310 days before
giving birth. Completed pregnancies are normally distributed with a mean of 266
days and a standard deviation of 16 days. Use statistical tables to determine the
probability that a completed pregnancy lasts i) at least 270 days, ii) at least 310
days.
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