9.2 & 9.3 Correlation & Regression

Paired Data -    x  and  y

... shoe size vs height   ... hrs exercise/week vs weight   ... shoe size vs salary

Scatter plots pg. 478

Pearson Correlation Coefficient

 

       -  Round to 3 decimal places

       -  values range from -1 to 1 ,
                strong inverse correlation to strong positive correlation
 
 
 

        -1 =================== 0=======================1
 
                 ( Sketch scatter plots above the number line )
 

 We  COULD actually compute r  - but we'll use the calculator

Using Table A-6         Always use =  0.5 column
 
  #2 pg. 490
 
 
 

Examples:
#6    pg. 491  & #6 pg. 505     Use Table A-6   for (=.05)
 

x Weight	29	35	28	44	25	34	30	33	28	24
y Fuel	31	27	29	25	31	29	28	28	28	33

Record and interpret r 

Write Equation if Appropriate:

Predict another value of y for a given value of x:
 
 
 
 

#8 pg. 491 and  #8 on pg. 507
 

Paper	2.41	7.57	9.55	8.82	8.72	6.96	6.83	11.42
Household Size	2	3	3	6	4	2	1	5

Record and interpret r 

Write Equation if Appropriate:

Predict another value of y for a given value of x:
 
 
 
 
 

 #16   use DATA set 4  -  and then predict for  #16 on pg. 507
 
 Record and interpret r 

Write Equation if Appropriate:

Predict another value of y for a given value of x:
 
 
 
 
 
 

COMMENTS:

 Common Errors - pg. 483
 

 Round of r  to 3 decimal places and a and  b to 3 significant digits

 
 Predictions - pg. 499; if significant use equation otherwise use 
 
 

 Guidelines of using Regression Equation - pg. 501