Grades
Boy
Girl
Total
117
130
247
Popular
50
91
141
Sports
Total
60
30
90
227
251
478
The table above indicates the number of randomly chosen 4 5, & 6 graders as to
whether their primary goal was to get good grades, to be popular, or to be good at
sports.
APexam = 6.97 + .1278 midterm
For every point you get on the miderm, we would expect your AP exam score to be
0.1278 higher.
Finding r:
Slope=r
Example: Fast food sandwiches
Protein:
X = 1 7 .2 g
sx = 14.6 g
Fat:
Y = 23.5 g
sy = 16.4 g
r=.83
sy
b1 = r ( )
Characteristics of the regression line:
1) It is important to correctly indicate the explanatory and response variables.
2) The least squares regression line always passes through the point ( X , Y ) .
3) The slope of the LSRL is
b1 = r
sy
sx .
4) The y
Example of a probability table:
Saturday
40%
60%
Sunday
70%
30%
100%
Rain
No Rain
100%
28% Rain Sat. and Sun.
18% No Rain Sat. and
Sun.
Rules of Basic Probability:
1.
2.Su m oftheprobabilitiesforallpossibleoutco m esinasa mplespacemusttotalone
3.P(notX )=
Lesson B2: The Wieland and Liza Problem
Given random variable x
E(x+c)= E(x)+c
(c is a constant)
E(x+y)= E(x)+E(y)
Standard deviation (x+y) or difference of standard deviations:
Example 1:
Wieland and Liza have cereal for breakfast each morning. Wieland h
Whenever a regression is run on the calculator, the residuals will be
placed in a list called resid.
To view a residual plot, follow the directions for a scatterplot: press
2nd staplot, turn the desired plot on, choose 1st type of plot, choose
explanatory
1) Form: linear
2) Direction (positive/ negative)
3) Strength: weak, moderate, strong
We describe the association between two variables.
The Correlation Coefficient:
The correlation coefficient, r, is the statistic that measures the strength and
direction
Standard Deviation Sx or x: The average distance the value of the variable is from the mean
Variance sx2 or x2
Resistant measure: A value that is relatively unaffected by changing a small proportion of the
total number of values
Density curve: Has an area