On average, men have more schooling than women.
Research Hypothesis
The difference between the population mean education of
men subtracted from the population mean education of
women is zero.
The difference between the population mean education of
men subtracted from the population mean education of
women is less than zero.
Null Hypothesis
Alternative Hypothesis
Cases
Dependent (O I R)
Independent (N (2))
All
R's education v21
Sex v2
Dependent Variable (Y)
Independent Variable (X)
Minimum
0
Minimum
1 male
Maximum
20
Maximum
2 female
Metric
Years of education Metric
Level of Measurement
Ratio
Value
(Code)
Value
Label
Number of
Cases
Group
Mean
Female
1034
12.2
1
Male
775
12.6
1809
-.40
N of Cases
1809

Level of Measurement
2
blank

na
blank
Degrees of
Freedom (d.f.)
1807
nominal
Graph
Mean
Difference
Test Statistic
P-value
-2.60
.009/2=.0045
One or Two
Tail Test
one
P-value
Relationship
Level of Significance
Decision
.0045
<
.01
Reject
I reject the null hypothesis that the population mean education of men
subtracted from the population mean education of women is zero (t = -2.60,
p<.01).
On average, males have 12.6 years of education and females have 12.2
years of education. Women have on average .4 of a year less education than

men. While this difference is statistically significant, it only a difference of
about 5 months of schooling.
One possible explanation for this difference may be that more women choose
to be full-time homemakers and not pursue further education. (You should be
able to come up with better explanations than this!)
Research Hypothesis: Male full-time workers make more money than female
full-time workers.
Null Hypothesis: The difference between the population mean income of men
subtracted from the population mean income of women is zero.
Alternative Hypothesis: The difference between the population mean income of
men subtracted from the population mean income of
women is less than zero.
Cases
Full time working people
(v23 = 1)
Dependent (O I R)
Respondent’s income
v31
Dependent Variable
Independent (N (2))
Sex v02
Independent Variable
Minimum
0
Minimum
1
Maximum
60,000
Maximum
2
Metric
dollars
Metric
Level of
Measurement
sex
Level of
Measurement
ratio
Value
(Code)
Value
Label
Number of
Cases
Group
Mean
2
Female
407
15,433.66
1
Male
470
24,387.23
blank
blank
877
-8953.57
nominal
Graph
Mean Difference
N of Cases
877
Degrees of
Freedom (d.f.)
875
P-value
Relationship
.000
<
Test Statistic
P-value
-10.821
.000
Level of Significance
.01
One or Two
Tail Test
one
Decision
Reject
Interpret:
 I reject the null hypothesis that the population mean income of men working
full-time subtracted from the population mean income of women working fulltime is zero (t = -10.821, p<.000).
 On average, males working full-time have an income of $24,387.23 and
females working full-time have an income of $15,433.66. Women make on
average $8,953.57 less income than men. This difference is statistically
significant, and it is also substantively significant (that is, it is a LOT of
money!)
 One possible explanation for this difference may be that even though
everyone in the sample is currently working full-time, men may have fewer
interruptions to their working careers. Women’s lower incomes may reflect
time out of the work force to care for children. Another possible explanation is
that men may be more likely to hold physically demanding jobs, or risky jobs
(such as firefighters), which tend to pay higher than other types of jobs. And
another explanation is that many of the jobs that women hold are in the low
paying “pink collar ghetto” (clerical positions), and the “brown collar ghetto”
(service jobs).
Research Hypothesis: Whites tend to marry later than blacks.
Null Hypothesis: The difference between the population mean age at first
marriage in whites subtracted from the population mean age
at first marriage in blacks is zero.
Alternative Hypothesis: The difference between the population mean age at
first marriage in whites subtracted from the population
mean age at first marriage in blacks is less than zero.
Cases
All
Dependent (O I R)
Respondent’s age at first
marriage (v17)
Dependent Variable
Independent (N (2))
Race v03
Independent Variable
Minimum
13
Minimum
1
Maximum
60
Maximum
2
Metric
age
Metric
Level of
Measurement
ratio
Level of
Measurement
race
Value
(Code)
Value
Label
Number of
Cases
Group
Mean
2
Black
377
22.13
1
White
1041
22.11
blank
blank
1418
0.02
nominal
Graph
Mean Difference
N of Cases
1418
Degrees of
Freedom (d.f.)
1416
P-value
Relationship
.2663
>
Interpret:
Test Statistic
P-value
-.084
.4665/2
Level of Significance
.05
One or Two
Tail Test
One
Decision
FAIL TO REJECT


I FAIL TO REJECT the null hypothesis that the population mean age at first
marriage among whites subtracted from the population mean age of first
marriage among blacks equals zero (t = -.084, p < .2663 or p >.05).
On average, whites age at first marriage is 22.11 and blacks age at first
marriage is 22.13. Although there is a difference of .02 years, this difference
is NOT statistically significant. The difference between the groups reflects
random sampling fluctuations only.
Research Hypothesis: People who own their own home are more satisfied with
their family life than people who do not own their own
home.
Null Hypothesis: The difference between the population mean satisfaction score
of those who own their home subtracted from the population
mean satisfaction score of those who do not own their own
home is zero.
Alternative Hypothesis: The difference between the population mean
satisfaction score of those who own their own home
subtracted from the population mean satisfaction score
of those who do not own their own home is less than
zero.
Cases
All
Dependent (O I R)
R’s satisfaction with
family life
(SATFAM = v76)
Dependent Variable
Independent (N (2))
Does respondent own or
rent home?
DWELLOWN (v34)
Independent Variable
Minimum
1
Minimum
1
Maximum
7
Maximum
2
Metric
Metric
none
Level of
Measurement
none
Level of
Measurement
ordinal
Value
(Code)
Value
Label
Number of
Cases
Group
Mean
2
Pays rent
660
5.50
1
Own or
buying
1094
6.07
1754
-0.57
blank
blank
nominal
Graph
Mean Difference
N of Cases
1754
Degrees of
Freedom (d.f.)
1752
P-value
Relationship
.000
<
Test Statistic
P-value
8.549
.000
Level of Significance
.01
One or Two
Tail Test
One
Decision
Reject null
hypothesis
Interpret:
 I reject the null hypothesis that the population mean satisfaction scores of
those who own their own home subtracted from the population mean
satisfaction scores of those who do not own their own home is zero (t = 8.549,
p<.000).
 On average, people who own their own homes have satisfaction scores of
6.07 (indicating a great deal of satisfaction with family life), while the
satisfaction scores of those who do not own their own home is 5.50. Those
who own their own home have a satisfaction score 0.57 satisfaction units
higher than those who rent.
 One possible explanation for this difference may be that those who own their
own home have more money, which brings with it more control over their
lives, and more autonomy. If they can afford to own their own home, it is
possible that they can also afford other things, like vacations, and time with
their families.