Statistics II

Question 1

Tools for Describing Data

Answer 1

Histograms
Box plots
bar chart
pie chart
trend charts

Question 2

Normal Distribution

Answer 2

The cornerstone of statistics
Bell-shaped
Symmetrical about the mean; roughly each side is a mirror image of the other
Generally only one common value; unimodal
Total area under curve = 1
Approximately 68% of distribution is within one standard deviation of the mean
Approximately 95% of distribution is within two standard deviations of the mean
Approximately 99.7% of distribution is within three standard deviations of the mean
Mean = median = mode

Question 3

Ratio-Mean-Standard Deviation-________

Answer 3

Histogram

Question 4

Interval- Mean- Standard deviation-________

Answer 4

Histogram

Question 5

Ordinal/ranked-median-interquartile range-

Answer 5

Box plot

Question 6

nominal/categorical-mode-(no common measure of spread)-_____

Answer 6

Bar Chart, pie chart

Question 7

Central Limit Theorem (CLT)

Answer 7

The CLT states that no matter how on-normal a body of data is distributed, if we sample the means (averages) from that data it can always form a normal distribution. The larger the value of the sample size (n), the better the approximation to the normal.

Question 8

Confidence Intervals

Answer 8

If the 95% confidence interval for the mean age in a study population extends from 26 to 34, a researcher can be 95% confident that the mean age of all employees (not just the ones randomly sampled for the study) is between 26 and 34 years.
A larger sample size will yield a narrower confidence interval.