Jan

Feb

Mar

Apr

May

Jun

Jul

Aug

Sep

Oct

Nov

Dec

38

30

46

40

46

49

47

50

50

42

37

37

Instructions

Answers

1.
Use the Chi-Square
Goodness-of-Fit test to see if there is a difference between the frequency of
homicides in different months of the year. Use a significance level of .05. Paste results here.

Num Categories: 12

Degrees of
freedom: 11

Expected Freq: 42.66667

Test Statistic,
X^2: 10.3750

Critical X^2: 19.67516

P-Value: 0.4970

2.
What are we trying to show
here?

3.
What is the p-value and what
does it represent in the context of this problem?

P-Value: 0.4970

4.
State in your own words what the results of
this Goodness-of-Fit test tells us.

5.
Repeat the above procedure using
only the summer months of Jun through Sep.
Paste results here. Did you get different results? Would these results support the police
commissioner’s claim that more homicides occur in the summer when the weather
is nicer.

Instructions

Answers

6.
Complete the table as
necessary.

[Hint:
You will need to compute the observed frequencies based on the percentages
for the 100 samples.

Rookies

Veterans

All-Stars

OBSERVED

50

45

5

EXPECTED

7.
Use the Chi-Square
Goodness-of-Fit test for Unequal Frequencies to see if there is a difference
between the observed frequencies and the expected frequencies Use a
significance level of .05.

Paste
results here.

8.
State the null and
alternative hypothesis.

9.
What conclusion would you
reach, given the result of your Goodness-of-Fit test? Does the data support the company’s claim?[State
in your own words following the guidelines for a conclusion statement learned
last week.]

Successful

Unsuccessful

Splint treatment

60

23

Surgery treatment

67

6

Instructions

Answers

10. Just looking at the numbers in the table, what is your best guess
about the relationship between type of treatment and success? Are they
independent or is there a relationship?

11. Compute a Chi-Square Test of Independence on this data using a 0.01 level of significance. Paste your results here.

12. What are the null and alternative hypothesis for this test?

13. What is the p-value for this result? What does this represent?

14. State your conclusion related to the context of this problem.

Example:Do not use this problem!!

State the problem that you are
analyzing.

Last year, I asked the kids in my
neighborhood what kind of cookies they preferred. 50% said chocolate-chip, 20% said
oatmeal-raisin, and 30% said sugar cookie.
I want to see if this has changed.

Make up some data for the new
situation.

I asked 50 neighborhood kids what kind
of cookie they preferred now and here’s what they said:

·
35 said chocolate-chip

·
5 said oatmeal-raisin

·
10 said sugar-cookie

Determine which type of Chi-Square
test you will perform.

Since these are unequal frequencies, I
will perform a Chi-Square Goodness-of-Fit Test (Unequal Frequencies).

Specify your null and alternative
hypotheses.

H0:
There is no difference this year in the preferences of cookies within
the neighborhood kids.

H1:
Things have changed.

Setup the test

Chocolate-Chip

Oatmeal-Raisin

Sugar-Cookie

OBSERVED

35

5

10

EXPECTED

25

10

15

Perform the test

Paste your STATDISK results here

State your conclusion

We have evidence to believe ….