Unit 3 part 1
What is type of skew does this represent:
Mode ≤ Median ≤ Mean
Right-skew
A disease impacts a total of 936 individuals in a population of 4000. What is the odds ratio?
117/500
You put 936/4000 in simplest terms
When might it not be appropriate to use mean as a measure of data?
When there are outliers
What are the 3 C’s of non-causal explanations?
1. Common Response
2. Confounding Response
3. Coincidence
What is the rule for a bell-curve?
68-95-99.7
What does a correlation of -.35 mean?
That it is a relatively weak, negative relationship
That it is a relatively weak, negative relationship
How do you calculate the inter-quartile range and how much of the data is representative of this range?
Q3 – Q1, 50%
What are the four steps of hypothesis testing?
1. Determine HO and H1
2. Collect data, and summarize with a single number or statistic
3. Determine how unlikely the test is if H0 is true
4. Make a decision
What percentage of the data falls within +1 SD of the mean?
34%
What is a residual?
The distance between a predicted value (estimate) and the actual value of observation
Which is presented in the standard units of measurement: Variation or Standard Deviation?
Standard Deviation
At Blergenhorsenfer University in St. Olaf, Minnesota, the admissions office has been accused of violating EEOC policies and discriminating against women in admissions, such that more men are recruited than women. How should they defend their recruitment methods?
By using a contingency table, they may compare the actual acceptance rates and demonstrate through association statistical analyses of whether or not there is a flaw in their methodology
What is the purpose and formula for a Z-Score?
To standardize scores for comparison:
(Score – mean (X)) / SD
What is the value for level of significance of a Chi-Square at .05?
3.84
What is the one type of graph we will never use and why?
Pie Charts; it is difficult to properly visualize the data
What is another way to calculate b and a in the y = a +bx?
b = corr(x,y) * SD (Y) / SD(X)
a= Mean(Y) – b * Mean(X)
Name 4 of the general rules for a good graph
1. Highlight the most interesting relationships.
2. Avoid distorting the data.
3. Start at the zero point
4. Use consistent formatting and style across a set of graphs.
5. Clearly define the data with titles, labels, legends and notes.
6. Minimize the ink-to-data ratio.
7. Avoid chart junk, unnecessary 3-D effects, excessive gridlines.
8. Avoid redundant labeling.
9. If you have to label things many times, you probably have chart junk!
10. Use only the data necessary to display the relationships.
11. Remember your numerical description summary statistics.
a. r^2 = .7^2 = .49Dr. Brown and Dr. Strasbaugh are conducting a study on managerial perceptions of creativity in accounting firms. Of their sample of 100, they determine a correlational relationship equal to +.70. What is the variability explained by this relationship?
r^2 = .7^2 = .49
What are the 3-key aspects of a distribution?
1. Location
2. Spread
3. Shape
What is baseline risk and why is it so important?
Baseline risk allows us to draw comparisons of whether or not a specific finding should be concerning to a population