Assignment 1 for STAT 203 – Statistics for Social Scientists
For problems solved by hand, show all work and calculations. For problems solved using SPSS (anything
that doesn’t say ‘by hand’), include only the relevant tables and graphs. For reading questions and
explanations, the best answer is almost never a single word or a large paragraph, but rather something
between the two. Datasets for the SPSS questions are available on the course webpage.
Due Monday May 21, 2012 at 7:30pm in the drop box in or near the statistics workshop.
Exercises by hand.
1. Consider the data set {15, 9, 7, 20, 4, 12, 8, 0, 31}, find, by hand, the…
a. …range
b. …median
c. …interquartile range
d. …outliers if any (or show there are none)
e. …mean.
f. Determine if this distribution is positively or negatively skewed. How do you know this
works?
2. The following frequency distribution below shows scores of people attitudes on lab-grown meat
from “Strongly Against” to “Strongly For”
Attitude Towards Lab Meat
Coded Attitude
f
Strongly Against
1
23
Somewhat Against
2
10
Slightly Against
3
2
Neutral
4
26
Slightly For
5
8
Somewhat For
6
17
Strongly For
7
14
N = 100
a. What type of data is this: categorical, ordinal, or interval?
b. Find, by hand, the cumulative frequency for each attitude.
c. Find the median.
d. What assumption must you make if the mean is to be meaningful?
e. Find the mean.
3. A survey was done to find the patterns in what made public school students successful
academically. One variable they found was related to success was the age of the child’s mother
when her first child was born. The crosstab of this data is below. *Data made up, but is designed to
match the findings explained by Gordon and Levitt in Freakanomics.
Child born before/after 30 * Academic Success Cross-tabulation
Count
Academic Success
Excellent Satisfactory
Mother’s age at first
childbirth.
Over 30
29
Marginal
45
Under 30
21
55
Total
50
100
a. What type is data is “Mother’s age at first childbirth”?
Total
18
92
32
50
108
200
b. What type of data is “Academic Success”?
c. Which of these variables is the dependent/response variable? Which is the
independent/explanatory variable? Explain how you know which is which.
d. What percentage of students are only marginally successful?
e. What is the ratio of students with mothers over 30 at childbirth to those under 30?
f.
Of the students whose mothers were under 30 at first childbirth, what percentage have
Satisfactory success or better?
Exercises for SPSS
4. A group of elementary school students were how lucky they felt from 0 (most unlucky) to 10
(most lucky). Their responses are found in the dataset Assn1Q4 – Luck online. *Data made up,
inspired by a textbook long ago.
a. What type of data is this?
b. Construct a histogram of the luck scores.
c. Describe the distribution of luck scores (description checklist: center, spread, shape, and
outliers).
d.
Build a frequency and a cumulative frequency table of the luck scores. How many
students reported that they were 2 or less lucky? What percentage of students said
they were 8 or more lucky?
e. Find the mean, median, skewness, and interquartile range.
f.
What would you infer about the perceived luckiness of the children polled?
5.
Consider the SPSS data Assn1Q5 set on the haircut costs of men and women in Canadian $.
*Data is a recreation of data from a previous statistics class.
a. Construct a side-by-side boxplot of the costs.
b. Describe and contrast the distributions of the costs.
c. Explain feature-by-feature why each of the distributions are so different.
d. Explain the outliers (unless you already did in part c).
Reading Questions
Outliers by Malcolm Gladwell, Ch.1 (The Matthew Effect). Everything you need for this chapter can be found in
the preview at books.google.com A direct link to the preview can be found on the course webpage.
1. Other than hockey skill, what makes the Canada world junior team an outlier among other
groups?
2. What was Gladwell’s explanation given for this group being an outlier.
3. What other system besides hockey does he claim this affects?
Elementary Statistics in Social Research. Ch.4 (Measures of Variability)
1. How are the variance and the standard deviation related?
Elementary Statistics in Social Research. Ch. 5 (Probability and the Normal Curve)
1. Describe the normal distribution.
2. What does the z-score or standard score indicate.
3. What does the addition rule assume about the outcomes being considered?