The goodness–of–fit test can be used to decide whether a population fits a given distribution, but it will not suffice to decide whether two populations follow the same unknown distribution. A different test, called the
test for homogeneity , can be used to draw a conclusion about whether two populations have the same distribution. To calculate the test statistic for a test for homogeneity, follow the same procedure as with the test of independence.
Note
The expected value for each cell needs to be at least five in order for you to use this test.
Hypotheses
H
0 : The distributions of the two populations are the same.
H
a : The distributions of the two populations are not the same.
Test statistic
Use a
test statistic. It is computed in the same way as the test for independence.
Degrees of freedom (
df )
df = number of columns - 1
Requirements
All values in the table must be greater than or equal to five.
Common uses
Comparing two populations. For example: men vs. women, before vs. after, east vs. west. The variable is categorical with more than two possible response values.
Do male and female college students have the same distribution of living arrangements? Use a level of significance of 0.05. Suppose that 250 randomly selected male college students and 300 randomly selected female college students were asked about their living arrangements: dormitory, apartment, with parents, other. The results are shown in
[link] . Do male and female college students have the same distribution of living arrangements?
Distribution of living arragements for college males and college females
Dormitory
Apartment
With Parents
Other
Males
72
84
49
45
Females
91
86
88
35
H
0 : The distribution of living arrangements for male college students is the same as the distribution of living arrangements for female college students.
H
a : The distribution of living arrangements for male college students is not the same as the distribution of living arrangements for female college students.
Degrees of Freedom (
df ): df = number of columns – 1 = 4 – 1 = 3
Distribution for the test:
Calculate the test statistic:χ2 = 10.1287 (calculator or computer)
Probability statement:p -value =
P (
χ2 >10.1287) = 0.0175
Press the
MATRX key and arrow over to
EDIT . Press
1:[A] . Press
2 ENTER 4 ENTER . Enter the table values by row. Press
ENTER after each. Press
2nd QUIT . Press
STAT and arrow over to
TESTS . Arrow down to
C:χ2-TEST . Press
ENTER . You should see
Observed:[A] and Expected:[B] . Arrow down to
Calculate . Press
ENTER . The test statistic is 10.1287 and the
p -value = 0.0175. Do the procedure a second time but arrow down to
Draw instead of
calculate .
Compare
α and the
p -value: Since no
α is given, assume
α = 0.05.
p -value = 0.0175.
α >
p -value.
Make a decision: Since
α >
p -value, reject
H
0 . This means that the distributions are not the same.
Conclusion: At a 5% level of significance, from the data, there is sufficient evidence to conclude that the distributions of living arrangements for male and female college students are not the same.
Notice that the conclusion is only that the distributions are not the same. We cannot use the test for homogeneity to draw any conclusions about how they differ.
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
