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RES 342 Week 5 E-Text Assignments

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

 !"#

 
Correlation Analysis Regression Analysis
(a) In correlation analysis, we calculate the
correlation coefficient which is a measure of the
degree of covariablity between X and Y
(b) Correlation is merely a tool to ascertain the degree
of relationship between X and Y. We can not assign
cause and effect relationship between X and Y
(a) Regression analysis is done to study the nature of
relationship between X and Y so that we may be able
to predict the value of one on the basis of the other
(b)In regression analysis we take X as the
independent variable and Y as the dependent variable.
This makes the study of cause and effect relation
between X and Y possible
(b) The correlation coefficient measures and reveals the degree of covariablity between X
and Y. It indicates the strength of relationship between X and Y.
(c) A correlation coefficient of ± 1 a perfect positive/negative correlation between X
and Y. A zero coefficient no correlation. Higher the value of r, stronger is the
correlation between X and Y.
(d) The sums needed are: xy, x^2 and y^2, where x = (X – Xbar) and y = (Y
Ybar)
(e) The two methods are: (a) t- test and (b) Z- test.
12.48$%X &"%Y &!
%n &'()*+"# 
#
,"%-""!* α &
#.(#"$"/(
" "#0F &t1
"#

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 Y = 0.0343X + 30.7963
 Degrees of freedom = 34, t
crit
= t
34, 0.025
= 
 Since t for slope is larger than the critical value, the null hypothesis is rejected.
Therefore, the population slope is different from zero.
 We are 95% confident that the true population slope lies somewhere in between
0.0101 and 0.0584.
 t
2
=
2.889
2
= 
12.50 $%X &2%Y &
2%n &34# 
#
,"%-""!* α &
#.(#"$"/(
" "#0F &t1
"#

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 Y = 0.0452X + 6.5763
 Degrees of freedom = 63, t
crit
= t
63, 0.025
= 
 Since t for slope is larger than the critical value, the null hypothesis is rejected.
Therefore, the population slope is different from zero.
 We are 95% confident that the true population slope lies somewhere in between
0.0342 and 0.0563.
 t
2
=
8.183
2
= 
13.30 -"
"Birthrate "5%... "6
LifeExp !"%InfMort %
Density """%GDPCap 7
*8""%Literate "#$"
#
 !"#$%$&'()"!!*###+%,#
#-$#!*#./"0,"!0!.##1"02 !"
$3456#!##)#7! !$#./)# !!#!*##./
!
13.32 -!"

Salary "9:
"n &41'%"
Year "
YearHire %Race 5
%.%Rank 5"%
.#

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