Question

Here is a bivariate data set in which you believe y to be the response variable.

x	y
28.7	65.1
26.6	66.2
29.1	61.1
27.7	69.3
28.9	62.9
25.5	65.3
24.3	66
25.9	66.3
27.2	65.6
85.6	45.1
19.9	66.5
30.4	64.3
24.7	64.8
33.7	61.5
26.4	65.4
25.8	64.9
34.5	62.3
20.9	66.6
26.4	64.9
29.6	64.2
25.8	65.4
27	65
31.3	63.7
24.9	65.2

Make a scatter plot of this data. Which point is an outlier?

(Enter as an ordered pair.)

Find the regression equation for the data set without the outlier.
   
(Enter as an equation in slope-intercept form with parameters rounded to three decimal places.)

Find the regression equation for the data set with the outlier.
   
(Enter as an equation in slope-intercept form with parameters rounded to three decimal places.)

Is this outlier an influential point?

• No, the outlier does not appear to be an influential point.
• Yes, the outlier appears to be an influential point.

Answer 1

SOLUTION- WE USE MINITAB-16 FOR CALCULATIONS

1.) STEPS- ENTER THE DATA> GRAPH> SCATTERPLOT> SELECT Y AS Y-VARIABLE AND X AS X-VARIABLE> OK.

THE OUTLIER POINT IS (85.6, 45.1)

2.) TO CONSTRUCT REGRESSION EQUATION WITHOUT OUTLIER-

STEPS-OMIT THE OUTLIER PAIR> STAT> REGRESSION> REGRESSION> SELECT Y AS RESPONSE AND X AS PREDICTOR> OK.

THE EQUATION IS Y=74.1 - 0.388X ; R-SQ= 42.6%

3.) TO CONSTRUCT REGRESSION EQUATION WITH OUTLIER-

STEPS- INCLUDE THE OUTLIER IN DATA SET> STAT> REGRESSION> REGRESSION> SELECT Y AS RESPONSE AND X AS PREDICTOR> OK.

THE EQUATION IS Y=74.1 - 0.339X ; R-SQ= 91.0%

4.) THE PRESENCE OF OUTLIER GIVES A BIGGER R-SQUARE VALUE. SO YES, THE OUTLIER IS AN INFLUENCIAL POINT.

****IN CASE OF DOUBT, COMMENT BELOW. ALSO LIKE THE SOLUTION, IF POSSIBLE.