Unit 3 Test

Question 1

Resistant to outliars

Answer 1

• median
• IQR
• Q1, Q3

Question 2

Not resistant to outliars

Answer 2

• mean
• range
• standard deviation
• variance
• r

Question 3

Correlation coefficient

Answer 3

• r
• measures how ‘tight’ points are to a line

-1

Question 4

Residuals

Answer 4

Difference between the observed value and predicted value

Question 5

Regression line

Answer 5

y=mx+b

y=b0 + b1x

Question 6

Slope

Answer 6

• built from the correlation and standard dev’s

* slope: b1 = r Sy/Sx

Question 7

Interpret slope

Answer 7

sci=34.6+.18days

“For each additional _________, you can expect an increase/decrease of about ____(slope) on your _______”

(“For each additional school day, you can expect an increase of about .18 pts on your science scores”)

Question 8

Calculate the residual

Answer 8

Actual y - predicted y

Question 9

Se= standard error

Answer 9

•standard dev of residuals

“For any given _____, you can expect a ______ of y=34.6+.18x, give or take about ____.”

(For any given school days, you can expect a science score of y=34.6 + .18x, give ir take about 4.2 pts)

Question 10

r^2

Answer 10

•percentage

“Approximately ___% of change in ______ can be explained by the change in _____”

(Approximately 34% of change in science scores can be explained by the change in school days)

Question 11

Residual plot

Answer 11

• horizontal scatter plot
• no pattern: good line
• pattern: bad

Question 12

Extrapolation

Answer 12

• Assuming the days continues

* Going outside the domain

Question 13

Influential scores

Answer 13

• Greatly affect regression equation
• change r^2 and slope drastically
• outliers in x-direction

Question 14

Outliers

Answer 14

In the y direction

Question 15

Correction does not equal causation

Answer 15

x never causes y

•lurking variables: causes changes