PPt Stats

Question 1

What is “data”?

Answer 1

1. A collection of information that describes the results of our experiment
2. A way to relate the dependent (response) variable, to the independent (explanatory) variable

Question 2

What is a mean?

Answer 2

The average of a data set

Question 3

What is Standard deviation?(R)

Answer 3

The square root of the variance

Question 4

What is variance? (R^2)

Answer 4

1. A measure of precision, the inherent variation or uncertainty in a data set
2. Your R^2 tells you how much of the variation in your dependent variable can be explained by your independent variable, vs. Just being due to random change
3. If R^2 = 1 then 100% of you patterns are due to the explanatory variable

Question 5

Bar Charts

Answer 5

Used to display means — NOT raw data

Question 6

Line Graphs

Answer 6

Used to display raw data over time

Question 7

Scatter plot

Answer 7

Useful in displaying raw data over time

Question 8

Histogram

Answer 8

1. Useful in displaying groups of data
2. Useful in showing the distribution of our data

Question 9

Pie Chart

Answer 9

1. Used to display ratios of raw data
2. Very good for visualizing categorical differences
3. Not so great from a stats perspective

Question 10

T Tests

Answer 10

1. Outcomes are not independent of each other
2. T-statistic
   (Mean of group 1 - Mean of group 2)/ sqrt(variance of group 1/sample size of group 1) + (variance of group 2/ sample size of group 2))

Question 11

What do t-tests tell us?

Answer 11

If there is significant statistical difference between the means of two groups

Question 12

P values

Answer 12

P values tell us how confident we can be in the relationship we’ve found between our independent and dependent variables

Question 13

What p value is considered significant for our purposes?

Answer 13

0.05 unless you are comparing more than 2 groups

Question 14

How do we know if our data is significant?

Answer 14

1. P-Values — the probability that our data is or isn’t random
2. What is our degrees of freedom
   2.5 how many categories we have (1), for 2 categories df=1, and with a 95% confidence interval we compare our p-value to P = 0.05
3. If our P-value < 0.05 the data is significant
4. Visually
5. Statistically

Question 15

Chi Square Review

Answer 15

1. “Either or data”
2. Outcomes are independent of each other
3. Our null hypothesis would predict that both categories react equally to the explanatory variable