The Practice of
Social Research
Chapter 14 – Quantitative Data Analysis
DR. JOE NJOROGE
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Quantification of Data
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Univariate Analysis
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Subgroup Comparisons
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Bivariate Analysis
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Introduction to Multivariate Analysis
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Sociological Diagnostics
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Ethics and Quantitative Data Analysis
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Quick Quiz
Quantification of Data
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Quantification Analysis – the numerical representation and manipulation of
observations for the purpose of describing and explaining the phenomena that
those observations reflect.
Quantification of Data
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Age
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1
= 1
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2
= 2
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3
= 3
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4
= 4
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5
= 5
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Sex
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Male = 1
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Female = 2
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Political Affiliation
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Democrat = 1
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Republican = 2
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Independent = 3
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Region of Country
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West = 1
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Midwest = 2
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South = 3
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Northeast = 4
Quantification of Data
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Develop Code Categories
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Use well-developed coding scheme.
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Generate codes from your data.
Quantification of Data
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Codebook Construction
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Codebook – the document used in data processing and analysis that tells the
location of different data items in a data file.
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The
codebook also identifies the locations of data items and the meaning of the
codes used.
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Purposes of the Codebook
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Primary guide in the coking processes
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Guide for locating variables
ATTEND
How
often do you attend religious services?
0. Never
1. Less than once a year
2. About once or twice a year
3. Several times a year
4. About once a month
5. 2-3 times a month
6. Nearly every week
7. Every week
8. Several times a week
9. Don’t know, No answer
Quantification of Data
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Data Entry
Univariate Analysis
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Univariate Analysis – the analysis of a single variable, for purposes of
description (examples: frequency distribution, averages, and measures of
dispersion).
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Example: Gender
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The
number of men in a sample/population and the number of women in a
sample/population.
Univariate Analysis
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Distributions
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Frequency Distributions – a description of the number of times the various
attributes of a variable are observed in a sample.
Univariate Analysis
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Central Tendency
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Average – an ambiguous term generally suggesting typical or normal – a central
tendency (examples: mean, median, mode).
Univariate Analysis
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Mean – an average computed by summing the values of several observations and
dividing by the number of observations.
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Mode- an average representing the most frequently observed value or attribute.
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Median – an average representing the value of the “middle” case in a
rank-ordered set of observations.
Univariate Analysis
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Practice: The following list represents the scores on a mid-term exam.
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100, 94, 88, 91, 75, 61, 93, 82, 70, 88, 71, 88
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Determine the mean.
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Determine the mode.
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Determine the median.
Univariate Analysis
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Dispersion – the distribution of values around some central value, such as an
average.
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Standard Deviation – a measure of dispersion around the mean, calculated so that
approximately 68 percent of the cases will lie within plus or minus one standard
deviation from the mean, 95 percent within two, and 99.9 percent within three
standard deviations.
Univariate Analysis
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Continuous Variable – a variable whose attributes form a steady progression,
such as age of income.
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Discrete Variable – a variable whose attributes are separate from one another,
such as gender or political affiliation.
Univariate Analysis
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Detail versus Manageability
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Provide reader with fullest degree of detail, balanced with presenting data in a
manageable form.
Subgroup Comparisons
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Description of subsets of cases, subjects or respondents.
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“Collapsing” Response Categories
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Handling “Don’t Knows”
Bivariate Analysis
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Bivariate Analysis – the analysis of two variables simultaneously, for the
purpose of determining the empirical relationship between them.
Bivariate Analysis
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Constructing a Bivariate Table
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Determine logical direction of relationship (independent variable and dependent
variable).
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Percentage down versus percentage across.
Bivariate Analysis
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Percentaging a Table
Bivariate Analysis
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Constructing and Reading Bivariate Tables
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Example: Gender and Attitude toward Sexual Equality
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The cases are divided into men and women.
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Each gender subgroup is described in terms of approval or disapproval of sexual
equality.
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Men and women are compared in terms of the percentages approving of sexual
equality.
Bivariate Analysis
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Contingency Table – a format for presenting the relationship among variables as
percentage distributions.
Bivariate Analysis
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Guidelines for Presentation of Tables
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A
table should have a heading or title that describes what is contained in the
table.
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Original content should be clearly presented.
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The attributes of each variable should be clearly indicated.
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The base on which percentage are computed should be indicated.
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Missing data should be indicated in the table.
Introduction to Multivariate Analysis
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Multivariate Analysis – the analysis of the simultaneous relationships among
several variables.