Georgetown Statistics

Update Summer 2014:

Just come to class.  No need to read anything on this site right now.

Update Spring 2014:

This is a quick gauge to measure the progress in your learnings about probability and statistics, through our course.  Please take no more than about 5 minutes to quickly answer (using gut instincts) most of these questions below.  You can then e-mail me your solutions.  At the end of our course we'll go through the same quiz questions, and we'll be able to diagnose areas you have improved and areas we need to spend more attention.  Thanks much.

1) Given that a warehouse has dozens of cubic boxes that are either 32 cubic feet, 64 cubic feet, or 96 cubic feet.  Two random boxes are selected and stacked atop one another.  What is the average height to the top of the box stack?

a. less than 8 feet

b. equal to 8 feet

c. greater than 8 feet

2) Which of the following comments are true?

a. the population variance calculation is an overestimate is used on a sample

b. the sample mean overestimates the population mean

c. the population variance unbiased estimates the sample variance

d. the sample mean underestimates the population mean

e. the population variance calculation is an underestimate if used on a sample

3) Given two simple regression outputs, the highest slope one has the higher correlation?

a. True

b. Fale

4) In hypothesis testing, if one rejects the null hypothesis at the 80% confidence level, then one can also always reject the null hypothesis at the:

a. 95% confidence level

b. 90% confidence level

c. 80% confidence level

d. 70% confidence level

5) Given we sample a U.S. cereal box weights, where the box states the weight is 16 ounces, +/- 4 ounces standard deviation.  Assuming a bell-shaped and symmetrical probability distribution, which of the following is true:

a. the population mean typically equals the sample mean

b. the sample mean become less biased with a larger sample

c. the sample mean become less biased with a smaller sample

d. the portion of the sample typically weighing between 8 ounces, and 24 ounces, is 95%

e. the sample weights have two modes

f. the population mean refers to the U.S. civilian population of nearly 400 million people

6) Given the probability of the shovel sales rising next week is 90%, and the probability of a snowstorm next week is 90%.  What is the approximate probability of next week shovel sales NOT rise, combined with there NOT being a snowstorm?

a. 100%

b. 99%

c. 90%

d. 81%

e. 50%

f. 10%

g. 1%

h. 0%

i. It depends on the sample sizes underlying these probabilities.

j. It depends on the covariance of these two events (rising shovel sales, and snowstormsj

Update Fall 2013:

For your take-home review is a sample of Ice Cream Sales after-tax data.  Provide initial thoughts on the data, strengths and weaknesses.  We'll discuss the solutions in class.