Download Soc 111—Introductory Sociology

Soc 111—Introductory Sociology
Survey Assignment
Purpose
The purpose of this assignment is to formulate a research question and develop a
hypothesis, collect data that can be used to test the hypothesis, test the hypothesis, and
draw a conclusion about the research question.
Context
This is the first of series of assignments whose purpose is to simulate the research process
that professional sociologists go through to produce knowledge. We won't necessarily be
taking these steps in the order that they actually occur, but when the series of assignments
are done, you will have some beginning experience with the entire process.
Audience
There really is no audience for this portion of the research process. Organizing a research
question and hypotheses and doing the statistical analysis is an important part of the
research process but not that you necessarily would present to others. So, in real life, you
would do this for yourself. But since we will be grading this, make sure that we can
understand what you have done.
Design
Make sure that your name(s) is (are) on your assignment. I think the easiest way to
complete the assignment is simply to cut and paste from the example below. However, you
are welcome to handwrite the assignment. Just make sure to follow all the steps as outlined
in the example.
Points
12.5
Soc 111—Introductory Sociology
Survey Assignment
1. Choose a research question as follows:
a. Select a dependent variable. It should be a variable that is a count of something, such as
number of hours slept. For example you might ask: “How many hours of sleep did you
get last night?” Try to make your question specific enough that you are likely to get good
information.
b. Select an independent variable. It should be a variable with two groups. For example,
males and females, lower classmen and upper classmen, or those born in Utah and those
born outside Utah, etc.
c. Ask your question to 10 people in each of the two groups for a total sample of 20 people.
2. Write a paragraph describing your research question, present a hypothesis identifying your
independent and dependent variables, and indicate briefly how you collected the data. Record
your responses in a table similar to the one below in whole numbers.
Example –
Our research question is “Does the amount of sleep students get vary by whether or not they live
on or off campus?” We hypothesize that students living in dorms will get more sleep on average
than students living off campus. Our dependent variable is the amount of sleep a student
reported for a weeknight, and our independent variable is whether or not they lived in the dorms
versus off campus. We asked 10 students living in the dorms on campus and 10 living off campus
how many hours they slept last night (all were in reference to a weeknight). There responses are
recorded below.
Dorms
Off campus
8
4
7
6
7
6
8
5
6
9
5
3
6
6
7
7
9
7
5
6
3. Calculate the mean, median, and mode and standard deviation for each group separately.
Please show your work. Give a brief interpretation.
Example –
Mean, Median, Mode
Dorms
5
5
Mode=7
6
Median=7
6
Mean = 6.8
7
median
7
7
8
8
9
(sum)68
Off-campus
3
4
5
6
6
6
6
7
7
9
(sum)59
(mean = 68/10 = 6.8)
(mode = 7, response with most cases)
(median = 7, point that divides distribution in half)
Standard Deviation
Dorms
Subtract
mean
x  x 
Square value
x  x 2
5
5
6
6
7
7
7
8
8
9
-1.8
-1.8
-.8
-.8
.2
.2
.2
1.2
1.2
2.2
3.24
3.24
.64
.64
.04
.04
.04
1.44
1.44
4.84
(sum)15.6
Mean x  = 6.8
 x  x 
2
2
Variance (s ) =
n 1
15.6
= 1.73

10  1
Standard deviation (s) = 1.73 = 1.32
median
(mean = 59/10=5.9)
(mode = 6, response with most cases)
(median = 6, point that divides distribution in half)
Off
campus
Example
-1.8 * -1.8 = 3.24
Example:
5 – 6.8 = -1.8
Mode = 6
Median = 6
Mean= 5.9
Subtract
mean
x  x 
Square value
Example:
3– 5.9 = -2.9
Example
-2.9 * -2.9 = 8.41
-2.9
-1.9
-0.9
.1
.1
.1
.1
1.1
1.1
3.1
8.41
3.61
.81
.01
.01
.01
.01
1.21
1.21
9.61
3
4
5
6
6
6
6
7
7
9
x  x 2
(sum)24.9
Mean x  = 5.9
 x  x 
2
2
Variance (s ) =
n 1
Standard deviation (s) =

24.9
= 2.77
10  1
2.77 = 1.66
Summary
Mean
STD
Dorms Off Campus
6.8
5.9
1.32
1.66
Interpretation: On average, students in the dorms reported sleeping 6.8 hours on a weeknight
and those living off campus reported sleeping 5.9 hours on average. There is more variation in
the hours slept among the off campus students compared to the students living in the dorms.
4. Calculate a two-mean t-test to compare the two group means to determine if they are
statistically different from each other. In other words, is 6.8 really different from 5.9, or is
the apparent difference due to an artifact of your data (e.g., small and/or select sample)?
Please show your work—it does not have to be typed. Give a brief interpretation of your
results.
Example –
First, you need to calculate the ‘pooled standard deviation’ (Sp) which an estimate of the
standard deviation of the population.
Sp 
(n1  1)s12  (n2  1) s 22
n1  n2  2
Sp 
(10  1)1.73  (10  1)2.77
 1.5
10  10  2
Then use the pooled standard deviation to calculate the t-value (the test statistic)
t
x1  x2
1 1
sp

n1 n2
t
6.8  5.9
.9

 1.34
1 1 .671
1.5

10 10
Compare your calculated t-value with t = 2.101. This is the appropriate t-value when there
are 18 degrees of freedom (n1 + n2 – 2 = 18) and we desire a 95 percent confidence level (p =
.05). If your value is greater than 2.101, then the difference between your means is
statistically significant, if lower than 2.101, then it is not significant (in other words, there is
more than a 5% chance your two means are not different).
1.34 < 2.101
not statistically significance at p < .05
Interpretation: Based on our t-test, the difference between the average hours of sleep students
in the dorms get compared to students off campus is not statistically significant. In other words,
there is no difference in how much sleep they get by whether they live on campus in the dorms, or
off campus. It is possible that this difference would be statistically different if we had a larger
sample size.