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**QUIZ**

Each question has either only one correct answer or one incorrect answer. The answers appear in the lower frame when you click on answer. Links to the appropriate sections of the text are also included.

1. A frequency distribution can be shown as

2. Simple statistics are

- for simpletons
- presented in stem and leaf plots
- things like correlations
- things like standard deviations

answer · Simple Statistics

3. What would you do with a median?

- Use it do show spread.
- Use it for normally distributed data.
- Cross it against oncoming traffic
- Indicate the middle of some data.

answer · Simple Statistics

4. The following are measures of spread:

- standard deviation
- root mean square errors
- percentile ranges
- polyunsaturated margarine

answer · the Spread

5. Which arrow indicates the standard error of the estimate?

6. A relative risk is

- a risk of matrimony
- an outcome statistic
- a relative of the odds ratio
- a relative frequency

answer · Relative Frequency

7. Differences between means are best thought about in terms of

- p values
- standard errors of the mean
- percentages of the mean
- standard deviations

answer · Effect Size · Mean ± SD or Mean ± SEM?

8. Dimension reduction

- describes loss of precision.
- describes factor analysis.
- is an example of ANOVA.
- is a weight-loss program.

answer · Dimension Reduction

9. Concerning reliability:

- It impacts most on descriptive studies.
- It can be expressed as an ICC.
- It can be expressed as a CV.
- It is quantified by 2-way ANOVA.

answer · Reliability

10. Concerning validity:

- It impacts most on descriptive studies.
- It is the correlation between true and observed values.
- A valid measure must be reliable.
- A reliable measure must be valid.

answer · Validity

11. Correct or incorrect expressions?

- height = 175 ± 6 cm
- VO2peak = 67 ± 5.1 ml/min/kg
- ICC = 0.87
- CV = 1.4%

answer · How Many Digits

12. Confidence intervals...

- are a new form of sprint training.
- are calculated routinely by most stats packages.
- define the likely range of a population value.
- are inferior to p values for indicating magnitude of
outcomes.

answer · Confidence Intervals · What is a P Value?

13. A correlation coefficient and its confidence interval are shown in the figure.

We can conclude that:

- The correlation is significant.
- The true value of the correlation is likely to be 0.45.
- More subjects should be tested.
- A type II error has occurred.

answer · More on the Lower and Upper Limits · Type II Errors

14. Concerning tests and test statistics:

- One-tailed tests are sometimes justified.
- Test statistics should always be shown.
- Chi-squared is a common test statistic.
- P = 0.06 means there is no effect.

answer · What is a P Value? · Using P Values

15. Many samples, each of 100 observations, are drawn from a population in which there is a correlation of 0.70 between two variables. How often would you expect to find a statistically significant correlation?

- hardly ever
- about one time in 100
- about one time in 20
- almost always.

answer · Type I Errors

16. What are appropriate comments about these data, which show mean weekly training durations for three groups of athletes? (Bars are SDs.)

- Differences between all groups are substantial. (See Effect Size.)
- The data should be analyzed by repeated-measures ANOVA.
- Log transformation appears to be necessary before analysis.
- Runners are lazier than cyclists.

answer · One-Way ANOVA

17. An outcome measured on a five-point scale (*not at all
*to *always*)...

- is an example of an ordinal variable.
- has a behavior problem when it comes to residuals.
- should be analyzed by logistic regression.
- can be analyzed by ANOVA.

answer ·Ordinal Dependent Variables

18. Log transform a variable...

- if the values are too big.
- if the residuals (error) get bigger for bigger values of the variable.
- if you don't get statistical significance.
- if non-parametric tests are inappropriate.

answer · Log Transformation · Non-Parametric Models

19. Non-parametric tests usually...

- are parametric tests in disguise..
- involve rank transformation of the dependent variable.
- work for grossly non-normal data..
- should be attempted if parametric tests give p > 0.05.

answer · Non-Parametric Models

20. If we studied the effect of gender and body mass on sprint performance time, we would use the following model:

21. Concerning multiple linear regression:

- Use it to fit curves as well as straight lines.
- Use it to control for the effect of numeric variables.
- It gives misleading results for highly correlated independent variables.
- Use it to fit multiple straight lines with several groups.

answer · Multiple Linear Regression

22. Repeated-measures models...

- are used in descriptive studies.
- can be analyzed by modeling variances.
- are used when you have to repeat a failed test.
- are straightforward to analyze with stats programs.

answer · Repeated-Measure ANOVA · RM·ANOVA: Three or more trials and no between·subjects effect

23. In a longitudinal study aimed at enhancing sport enjoyment, the following results were obtained

We can conclude that:

- Initial randomization to the two groups was poor.
- There is one between- and one within-subject factor.
- The time effect in the model is substantial.
- The time effect in the model is significant.

answer · Two trials plus...

24. Concerning sample sizes for a controlled longitudinal study:

- Sample size is proportional to (1 - r), where r = reliability correlation.
- Controlled studies need 4x as many subjects as uncontrolled studies.
- Get sample size "on the fly" by testing until you get an acceptable confidence interval.
- None of the above.

answer · What Determines Sample Size · Sample Size "On the Fly"

25. The size of a sample needed for a cross-sectional study...

- depends on the size of your research grant.
- is inversely proportional to the square of the validities of your measures.
- is a function of the largest effect you want to detect.
- depends on how many student researchers you have on the
project.

answer · The Right Number of Subjects · What Determines Sample Size

26. When you come home from climbing in the statistical mountains, you will tell the folks, amongst other things, that...

- from now on you will show as few numbers as possible.
- statistical modeling is no substitute for knowing your data.
- it's important to play with stats programs.
- from now on you will test rather that estimate.

answer · Summary

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Last updated 25 April 97