Here are my answers:
Change everything you see, I don’t want anybody to get caught cheating.
Problem # 1
What is the proceedure used to find the equations from which the parameters a & b of the
'leastsquares' line y = a + bx are found?
Answer:
First of all, a sample of data of a certain population is collected and looked at point by
point.
A process called Linear regression is used to obtain the linear regression equation
y=a+bx.
In this process the regression curve approximates the mean value of the data.
The constants a and b are determined by solving simultaneously the equations:
2
y
an b
x
xy
a
x b
x
=
+
=
+
Where a is the yintercept, and b is the slope of the resulting linear equation.
Solving
them for the data we get:
1
1
n
n
i
i
i
i
y
b
x
a
n
=
=

=
1
1
1
2
2
1
1
(
)
n
n
n
i i
i
i
i
i
i
n
n
i
i
i
i
n
x y
x
y
b
n
x
x
=
=
=
=
=

=

This preview has intentionally blurred sections. Sign up to view the full version.
View Full DocumentQuestion 2
In the past the weight of a given production item was 40 ounces with a standard deviation
of .32 ounce. A random sample of 20 items showed a standared deviation of .25. Is the
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '08
 Clark
 Statistics, Normal Distribution, Regression Analysis, Yi

Click to edit the document details