home
***
CD-ROM
|
disk
|
FTP
|
other
***
search
/
Shareware Overload
/
ShartewareOverload.cdr
/
educ
/
freest2.zip
/
REGRESS.HLP
< prev
next >
Wrap
Text File
|
1991-04-11
|
6KB
|
224 lines
╔═══════════╗
║ ███ ▄ ███ ║ CHAPTER 4
║ ▀▀▀▀▀▀▀▀▀ ║
║ ▄▄▄▄▄▄▄▄▄ ║ ELEMENTARY REGRESSION
║ ███ ▀ ███ ║
╚═══════════╝
The "Elementary Regression" module of FREESTAT is provided for
those who may need to conduct a simple regression analysis by
entering data from the keyboard. Thus, it can be a very handy
labor saver for those quick and dirty jobs. In addition to the
simple regression procedures, you may also conduct multiple
regression using two independent variables.
VARIABLE TRANSFORMATIONS
The regression procedures will also permit data transformations
if you elect to use raw data input. The permissible
transformations are:
A X = X + a a = Numerical constant
B X = X * b b = Numerical constant
C X = 1/X Reciprocal transformation
D X = SQRT(X) Square root transformation
E X = LN(X) Naperian logarithm
F X = LN10(X) Common logarithm
G X = ARCSIN(X) Arcsin transformation
H X = LOGIT(X) Logit transformation
I X = PROBIT(X) Probit transformation
J X = X^y Power of y = Numerical constant
K Cancel transformations
When you choose the option to transform a variable, the above
transformations will be presented to you for selection. The
transformations will be carried out in the order in which you
choose them. It is very important that you understand how that
works.
Suppose, for example, that you want to transform X such that X
= 14 + 3 * X. You would first choose Option B and then enter the
value of 3. You would then choose Option A and then enter the
value of 14. The resulting transformation would then be:
X = (X * 3) + 14
Now consider what would happen if you chose Option A first and
then Option B. If you chose Option A and then entered 14 you
would have X = X + 14. If you then chose Option B and entered
the value of 3, you would have the transformation,
X = (X + 14) * 3
which would be incorrect. Just remember, all transformations are
executed in the order they are selected.
BIVARIATE REGRESSION
The bivariate regression procedure enables you to conduct
simple linear regression analyses of the form:
Simple linear regression -- Y = a + bX + e
Geometric regression -- Y = a * X^b, and
Exponential regression -- Y = a * b^X
The following is a sample of the output generated by the
bivariate regression procedure using summary data and simple
linear regression.
Simple Linear Regression
Mean of Y = 34.90000
Mean of X = 18.30000
SD of Y = 12.80000
SD of X = 8.30000
r = 0.64000
N = 300
Sum y^2 = 48988.16000
Sum x^2 = 20598.11000
Sum xy = 20330.08640
Regression of Y on X
Slope b = 0.98699
Correlation r = 0.64000
Explained SS ESS = 20065.55034
Residual SS RSS = 28922.60966
Std error SE = 9.85169
F-ratio = 206.74255
p <= 0.00000
95% Confidence Intervals
15.72330 <= a <= 17.95294
0.85245 <= b <= 1.12153
0.56792 <= r <= 0.70234
Regression of X on Y
Intercept a = 3.81650
Slope b = 0.41500
Correlation r = 0.64000
Explained SS ESS = 8436.98586
Residual SS RSS = 12161.12414
Std error SE = 6.38820
F-ratio = 206.74255
p <= 0.00000
95% Confidence Intervals
3.09361 <= a <= 4.53939
0.32776 <= b <= 0.50224
0.56792 <= r <= 0.70234
Estimated Values
For the model, Y' = a + bX
X = 27.00000
Y' = 43.48680
95% Interval for Mean
41.87035 <= Y' <= 45.10324
95% Interval for Individual Value
24.10995 <= Y' <= 62.86364
For the model, Y' = a + bX
X = 11.00000
Y' = 27.69499
95% Interval for Mean
26.20924 <= Y' <= 29.18073
95% Interval for Individual Value
8.32861 <= Y' <= 47.06137
MULTIPLE REGRESSION
As indicated above, the multiple regression procedure allows
you to enter two independent variables and one dependent
variable. Once you have obtained your fitted model, you may
elect to produce estimated values of your dependent variable, Y',
for values of X1 and X2 that you wish to enter.
The following is a sample of the output generated by the
multiple regression procedure.
Summary Data
Mean of Y = 25.00000
Mean of X1 = 47.00000
Mean of X2 = 83.00000
SD of Y = 11.00000
SD of X1 = 21.00000
SD of X2 = 28.00000
N = 290
Sum y^2 = 34969.00000
Sum x1^2 = 127449.00000
Sum x2^2 = 226576.00000
Sum yx1 = 22698.06000
Sum yx2 = 37385.04000
Sum x1x2 = 28888.44000
Multiple R = 0.50069
R-Square = 0.25069
r(y,x1) = 0.34000
r(y,x1)^2 = 0.11560
r(y,x2) = 0.42000
r(y,x2)^2 = 0.17640
r(x1,x2) = 0.17000
r(x1,x2)^2 = 0.02890
F = 96.35516 p <= 0.0000
Semi-partial & partial correlations
sr(y,x1) = 0.27257
sr(y,x1)^2 = 0.07429
sr(y,x2) = 0.36755
sr(y,x2)^2 = 0.13509
pr(y,x1) = 0.30034
pr(y,x1)^2 = 0.09021
pr(y,x2) = 0.39083
pr(y,x2)^2 = 0.15275
Raw Score Model
a = 6.02875
b1 = 0.14488
b2 = 0.14653
Standardized Model
Beta 1 = 0.27659
Beta 2 = 0.37298
95 Percent Confidence Intervals
0.40877 <= R <= 0.58256
0.23379 <= r( y,x1) <= 0.43819
0.32013 <= r( y,x2) <= 0.51064
0.05571 <= r(x1,x2) <= 0.27989
0.16209 <= sr1 <= 0.37629
0.26315 <= sr2 <= 0.46344
0.19140 <= pr1 <= 0.40197
0.28827 <= pr2 <= 0.48453
ssy = 34969.00000
ssy' = 8766.48451
ssx1 = 2597.95291
ssx2 = 4724.06811
sse = 26202.51549
Std Err y = 9.55500
SE b1 = 0.05630
SE b2 = 0.05433
4.92901 <= a1 <= 7.12848
0.08708 <= b1 <= 0.20269
0.10469 <= b2 <= 0.18836
Estimated Values
For the model Y'= a + b1X1 +b2X2
X1 = 37.00000
X2 = 44.00000
Y' = 17.83660
For the model Y'= a + b1X1 +b2X2
X1 = 57.00000
X2 = 69.00000
Y' = 24.39744
END OF CHAPTER