Statistic work
mehett
regression.pdf
Regression?
Categorical/Ordinal
Dependent Variable
Interval Dependent
Variable
Categorical/ Ordinal
Independent Variable Chi Square Difference of Means
Interval Independent
Variable Not Covered! Correlation OR
Regression (bivariate)
Regression Analysis
• Similar to correlation analysis in many ways • Requires interval level dependent variables
• Similar calculations
• More precisely specifies the relationship between X and Y • The independent variable X is used to predict values of the dependent
variable Y
• The coefficient on X tells us the effect of a one unit change in X on our predicted value of Y
Regression Intuition
Y Intercept or a Slope or b
Regression Analysis
Regression Analysis
Y = a + bX
Y = 1.30 + .59(X)
Regression Analysis
Y = 14 + 3X
Calculating the Regression Line
Calculating b: Specific Steps
Calculating a: Specific Steps
Drawing the Regression Line
Using the Regression Line for Prediction
Regression Analysis- Example
X Y XY
1 2
3 3
3 5
4 6
5 8
5 4
7 7
1
9
9
16
25
25
49
134
4
9
25
36
64
16
49
203
2
9
15
24
40
20
49
159
Regression Analysis- Example
Y = 1.56 + .86 X
(1.56, 0)
(4, 5)
Regression Analysis- Example
X Y XY
5 10
3 9
6 7
6 8
10 6
25
9
36
36
100
206
100
81
49
64
36
330
50
27
42
48
60
227
Regression Analysis- Example
Y = 11 + (-.5)(X)
(11, 0)
(6,8)
Regression Exercise
• Suppose we hypothesis that people who miss class more often perform worse academically. To test the hypothesis we ask four people how many classes they missed and their GPA. Use regression analysis to calculate the effect of missing class on a person’s expected GPA. Do the results support our hypothesis?
# of Absences GPA
0 4.0
2 3.0
3 3.0
7 2.0
