Null Hypothesis
H
0 : The population correlation coefficient IS NOT significantly different from zero. There IS NOT a significant linear relationship(correlation) between
x and
y in the population.
Alternate Hypothesis
H
a : The population correlation coefficient IS significantly DIFFERENT FROM zero. There IS A SIGNIFICANT LINEAR RELATIONSHIP (correlation) between
x and
y in the population.
Drawing a conclusion:
There are two methods of making the decision. The two methods are equivalent and give the same result.
Method 1: Using the
p -value
Method 2: Using a table of critical values
In this chapter of this textbook, we will always use a significance level of 5%,
α = 0.05
Note
Using the
p -value method, you could choose any appropriate significance level you want; you are not limited to using
α = 0.05. But the table of critical values provided in this textbook assumes that we are using a significance level of 5%,
α = 0.05. (If we wanted to use a different significance level than 5% with the critical value method, we would need different tables of critical values that are not provided in this textbook.)
Method 1: using a
p -value to make a decision
To calculate the
p -value using LinRegTTEST:
On the LinRegTTEST input screen, on the line prompt for
β or
ρ , highlight "
≠ 0 "
The output screen shows the p-value on the line that reads "p =".
(Most computer statistical software can calculate the
p -value.)
If the
p -value is less than the significance level (
α = 0.05):
Decision: Reject the null hypothesis.
Conclusion: "There is sufficient evidence to conclude that there is a significant linear relationship between
x and
y because the correlation coefficient is significantly different from zero."
If the
p -value is not less than the significance level (
α = 0.05)
Decision: DO NOT REJECT the null hypothesis.
Conclusion: "There is insufficient evidence to conclude that there is a significant linear relationship between
x and
y because the correlation coefficient is NOT significantly different from zero."
Calculation notes:
You will use technology to calculate the
p -value. The following describes the calculations to compute the test statistics and the
p -value:
The
p -value is calculated using a
t -distribution with
n - 2 degrees of freedom.
The formula for the test statistic is
. The value of the test statistic,
t , is shown in the computer or calculator output along with the
p -value. The test statistic
t has the same sign as the correlation coefficient
r .
The
p -value is the combined area in both tails.
An alternative way to calculate the
p -value
(p) given by LinRegTTest is the command 2*tcdf(abs(t),10^99, n-2) in 2nd DISTR.
The line of best fit is: ŷ = -173.51 + 4.83
x with
r = 0.6631 and there are
n = 11 data points.
Can the regression line be used for prediction?
Given a third exam score (
x value), can we
use the line to predict the final exam score (predicted
y value)?
H
0 :
ρ = 0
H
a :
ρ ≠ 0
α = 0.05
The
p -value is 0.026 (from LinRegTTest on your calculator or from computer software).
The
p -value, 0.026, is less than the significance level of
α = 0.05.
Decision: Reject the Null Hypothesis
H
0
Conclusion: There is sufficient evidence to conclude that there is a significant linear relationship between the third exam score (
x ) and the final exam score (
y ) because the correlation coefficient is significantly different from zero.
Wayne and Dennis like to ride the bike path from Riverside Park to the beach. Dennis’s speed is seven miles per hour faster than Wayne’s speed, so it takes Wayne 2 hours to ride to the beach while it takes Dennis 1.5 hours for the ride. Find the speed of both bikers.
from theory: distance [miles] = speed [mph] × time [hours]
info #1
speed_Dennis × 1.5 = speed_Wayne × 2
=> speed_Wayne = 0.75 × speed_Dennis (i)
info #2
speed_Dennis = speed_Wayne + 7 [mph] (ii)
use (i) in (ii) => [...]
speed_Dennis = 28 mph
speed_Wayne = 21 mph
George
Let W be Wayne's speed in miles per hour and D be Dennis's speed in miles per hour. We know that W + 7 = D and W * 2 = D * 1.5.
Substituting the first equation into the second:
W * 2 = (W + 7) * 1.5
W * 2 = W * 1.5 + 7 * 1.5
0.5 * W = 7 * 1.5
W = 7 * 3 or 21
W is 21
D = W + 7
D = 21 + 7
D = 28
Salma
Devon is 32 32 years older than his son, Milan. The sum of both their ages is 54 54. Using the variables d d and m m to represent the ages of Devon and Milan, respectively, write a system of equations to describe this situation. Enter the equations below, separated by a comma.
please why is it that the 0is in the place of ten thousand
Grace
Send the example to me here and let me see
Stephen
A meditation garden is in the shape of a right triangle, with one leg 7 feet. The length of the hypotenuse is one more than the length of one of the other legs. Find the lengths of the hypotenuse and the other leg
however, may I ask you some questions about Algarba?
Amoon
hi
Enock
what the last part of the problem mean?
Roger
The Jones family took a 15 mile canoe ride down the Indian River in three hours. After lunch, the return trip back up the river took five hours. Find the rate, in mph, of the canoe in still water and the rate of the current.
Shakir works at a computer store. His weekly pay will be either a fixed amount, $925, or $500 plus 12% of his total sales. How much should his total sales be for his variable pay option to exceed the fixed amount of $925.
I'm guessing, but it's somewhere around $4335.00 I think
Lewis
12% of sales will need to exceed 925 - 500, or 425 to exceed fixed amount option. What amount of sales does that equal? 425 ÷ (12÷100) = 3541.67. So the answer is sales greater than 3541.67.
Check:
Sales = 3542
Commission 12%=425.04
Pay = 500 + 425.04 = 925.04.
925.04 > 925.00
Munster
difference between rational and irrational numbers
Jazmine trained for 3 hours on Saturday. She ran 8 miles and then biked 24 miles. Her biking speed is 4 mph faster than her running speed. What is her running speed?
