Microsoft Office Tutorials and References

In Depth Information

Problems and Exercises

1. What is the difference between time series and cross-sectional data? Give

examples of both?

2. What are the three principle approaches we discussed for performing data

analysis in Excel?

3. What is a frequency distribution?

4. Frequency distributions are often of little use with time series data. Why?

5. What are three statistics that provide location information of a frequency

distribution?

6. What are two statistics describing the dispersion or variation of frequency

distributions?

7. What does a measure of positive skewness suggest about a frequency distribu-

tion?

8. If a distribution is perfectly symmetrical, what can be said about its mean,

median, and mode?

9. How are histograms and frequency distributions related?

10. What is the difference between a sample and a population?

11. Why do we construct conﬁdence intervals?

12. Are we more of less conﬁdent that a sampling process will capture the true

population mean if the level conﬁdence is 95 or 99%?

13. What happens to the overall length of a conﬁdence interval as we are required

to be more certain about capturing the true population mean?

14. What is the difference between an independent variable and dependent variable

in regression analysis?

15. You read in a newspaper article that a Russian scientist has announced that he

can predict the fall enrollment of students at Inner Mongolia University (IMU)

by tracking last spring’s wheat harvest in metric tons in Montana, USA.

a. What are the scientist’s independent and dependent variables?

b. You are dean of students at IMU, so this announcement is of importance for

your planning. But you are skeptical, so you call the scientist in Moscow to

ask him about the accuracy of the model. What measures of ﬁt or accuracy

will you ask the scientist to provide?

16. The Russian scientist provides you with an alpha (1040) and a beta (38.8) for

the regression. If the spring wheat harvest in Montana is 230 metric tons, what

is your prediction for enrollment?

17. The Russian scientist claims the sum of all residuals for his model is zero and

therefore it is a perfect ﬁt. Is he right? Why or why not?

18. What
Signiﬁcance F
would you rather have if you are interested in having a

model with a signiﬁcant association between the independent and dependent

variables—0.000213 or 0.0213?

19. In the covariance matrix below, answer the following questions:

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