QUANTITATIVE METHODS

I203 Social and Organizational Issues of Information

A Problem…

Yoogle.com wants to better understand the concept of ‘credibility’ in information. In particular, they want to know more about how their users make judgments about credibility in information.

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(photo courtesy of dailyhaha.com)

(Induction)

(Deduction)

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Inductive Logic of Research in Qualitative Studies

Generalizations are made, or Theories to Past ExperienceAnd Literature

Researcher Looks for Broad Patterns, Generalizations, or Theories from Themes or Categories

Researcher Analyzes Data to Form ThemesOr Categories

Researcher Asks Open-Ended Questions of ParticipantsOr Records Field Notes

Researcher Gathers Information

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The Deductive Approach in Typical Quantitative Research

Researcher Tests or Verifies a Theory

Researcher Tests Hypotheses or Research QuestionsFrom the Theory

Researcher Defines and OperationalizesVariables Derived from the Theory

Researcher Measures or Observes Variables Using anInstrument to Obtain Scores

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If our goal is to find support (or not) for a theory or hypothesis, how do we establish such a relationship?

…and if we do establish a relationship, how do we know?

Research types and causality: Descriptive

Descriptive Summarize data Statistics:

histograms, means, percentages

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Research types and causality: Associational

Associational Only to relate variables Predictions only made to

show that a relationship exists

This is where test statistics (t, F, Chi-Square) become important, along with the p-value (essentially the probability associated with the statistic)

Statistics: Correlation, Multiple Regression

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Research types and causality: Comparative

Comparative Compares two or more groups Looking for difference between groups Common Statistics: t-tests, ANOVA (inferential

statistics)

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Independent Samples Test

.583 .456 2.715 17 .015 6.083 2.241 1.355 10.811

2.013 2.337 .163 6.083 3.022 -5.278 17.445

Equal variancesassumed

Equal variancesnot assumed

ageF Sig.

Levene's Test forEquality of Variances

t df Sig. (2-tailed)Mean

DifferenceStd. ErrorDifference Lower Upper

95% ConfidenceInterval of the

Difference

t-test for Equality of Means

Group Statistics

3 34.33 5.033 2.906

16 28.25 3.317 .829

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ageN Mean Std. Deviation

Std. ErrorMean

Questionnaires, Surveys

Experiments and Experimental Designs

Common Types of Quantitative Research Methods (Methods of Research)

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Surveys

Method of Analysis

Rely on existing variation in the sample population to obtain a ‘representative sample’.

Surveys also control for the influence of external factors by asking lots of questions from the same people.

Surveys are not the same thing as Questionnaires!

That is, in-depth interviews, observation, content analysis could also be used in survey research.

Questionnaires are a specific method for obtaining a structured set of survey data. 11

Potential Problems in Questionnaires and Surveys

Obtaining a representative sample 1930’s Literary Digest poll:

Franklin Roosevelt predicted to lose the 1936 presidential election by a landslide.

Oops… he won by a landslide.

Accounting for outliers in sample What is the best undergraduate major if

you want a high income (UNC-Chapel Hill survey)? One outlier, a geography major named

Michael Jordan, accounted for the huge skew in average salaries for graduates (at the time he made $80 million/year) 12

Advantages and Disadvantages of Surveys and Questionnaires

Advantages Can be easily scaled for small or large studies Allows researcher to collect a lot of data on a wide

range of topics

Disadvantages Sampling becomes a big issue if you want to

generalize to larger population Most survey data cannot be used for true causal

tests However, Longitudinal data can help alleviate this

problem (but not completely)13

Experiments14

Little Albert

Milgram’s Authority Experiment

What to look for in a Quantitative Study: Conditions of Causality

Covariation

Non-spurious relationship

Logical time ordering

Mechanism to explain how X causes Y

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X Y

True Randomized Experimental Design

(1) Independent Variables are manipulated (usually by experimenter, sometimes by

context)

(2) Participants must be assigned randomly to various conditions or groups When this condition is not met, it is a quasi-

experimental design

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Common Experimental Designs

R

O

O

X O

O

R

X

O

O

R

O

O

X O

O

(1)

(2)

X O (3)

O (4)

Pretest-Posttest Control

Post-only Control

Solomon 4-group

Experiments

Advantages Gives researcher tight control over independent factors Allows researcher to test key relationships with as few

confounding factors as possible Allows for direct causal testing

Disadvantages Usually a smaller N and number of independent

variables than surveys. Sometimes give up large amounts of generalizability in

favor of direct causal analysis and controls. Require a large amount of planning, training, and time.

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Making Sense of Quantitative Studies Think about the sample, who does this represent?

Read the ‘Methods’ section…how did they create their measures? Do you believe that the measures represent the intended concept(s)?

What are the potential confounding variables?

Think about the generalizability of the study.

Think about whether the analysis is claiming to be a test of causality (what was the method? How is causality established)?

Interpretation matters just as much in a quantitative study as a qualitative study!

Mixed Methodologies Win

Puts the emphasis on the problem, not the method Many combinations found

in broad range of research topics: Experiment /

Questionnaires Field Study / Experiment Interviews /

Questionnaires Participant Observation /

Experiments

Can also include using both qualitative and quantitative methods of measurement in a single study.

Assignment 1

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