URBP 204A QUANTITATIVE METHODS I

Survey Research II

Gregory NewmarkSan Jose State University

(This lecture is based on Chapters 4 & 6 of Earl Babbie’sThe Practice of Social Research, 10th Edition.

All uncredited cartoons are from CAUSEweb.org by J.B. Landers.)

Research Purposes• Exploration• Description • Explanation

Research Purposes• Exploration – to ‘get to know’ a new topic– Examples• “What is transit oriented development?”• “What is equity planning?”

– Purposes• To satisfy researcher’s curiosity • To test the feasibility of more extensive study• To develop methods to be employed in future study

– Benefits and Drawbacks• Breaks new ground and yields new insights• Seldom provides satisfactory answers

Research Purposes• Description – to describe observations– Examples• “What are the characteristics of TOD in California?”• “How does this equity planning program work?”

– Purposes• To describe situations and events• To chronicle activities

– Benefits and Drawbacks• Answers questions of what, where, when, and how• Does not answer why

Research Purposes• Explanation – to explain phenomena– Examples• “Why are TODs not more successful in California?”• “Why does this equity planning program work so well?”

– Purposes• To explain things• To understand why something occurred

– Benefits and Drawbacks• Causality

Explanation• How do you know if your explanation is

credible?

Nomothetic Causality• Real Criteria– Correlation• A relationship exists between variables• “Housing values are negatively related to commute

length”

– Time Order• Cause precedes effect• “Gender impacts political opinions”

– Non-Spurious (Non Coincidental)• Effect can not be explained by a third variable• “Height is not explained by Zodiac sign”

Nomothetic Causality• Why is correlation not enough for causality

here?

Nomothetic Causality• Does this cartoon pass the causality criteria?

Nomothetic Causality• False Criteria– Complete Causation• Nomothetic explanations are usually incomplete• “Three common factors for driving a Prius are . . .”

– Exceptional Cases• Nomothetic explanations are not voided by exceptions• “I am an environmentalist, but I don’t drive a Prius.”

– Majority of Cases• Nomothetic explanations still valid even if effect only

occurs in the minority of cases• “Most environmentalists don’t drive a Prius.”

Nomothetic Causality• Necessary Causes– Represents a condition that must be present for

the effect to follow• “You need to be female to get pregnant”• “You need to go to college to get a college degree”

• Sufficient Causes– Represents a condition that guarantees effect will

follow• “Skipping the final exam will result in automatic failure”• “Participating in our survey will get you a t-shirt”

Nomothetic Causality• Unit of Analysis– What or whom are being studied• Individuals, groups, organizations, social artifacts, etc.• Typically, but not always, the unit of observation

– For example, a study of couples might observe both partners separately

– Data from individual units can be aggregated• “32 percent of our sample is college educated”• “This neighborhood predominantly does not vote”

Nomothetic Causality• Faulty Reasoning regarding Units of Analysis– Ecological Fallacy• Drawing conclusions about individual based on

observation of groups• “Younger neighborhoods support recycling, therefore

younger people are more likely to support recycling”

– Reductionism• Explaining complex phenomena with narrow concepts• Oversimplification• “What is the single cause of the American Revolution?”• “Economists see everything in economic terms.”

Nomothetic Causality• Ecological Fallacy

Nomothetic Causality• Reductionism

Time Dimension of Research• Cross-Sectional Studies– Observations are all made at one point in time– E.g. our FWBT survey

• Longitudinal Studies– Observations are extended over time– Trend Studies track a characteristic– Cohort Studies track a subpopulation– Panel Studies track the same people (the panel)• Problem of panel attrition (dropping out of the study)

The Research Proposal• Problem/ objective of research• Relevance of research• Literature review• Research question• Hypothesis • Variables of interest • Research method/s• Types of data to be collected - methods, sources• Plan for data analysis• Outline of research report - main chapters, sub-chapters• References/ Bibliography• Schedule • Budget

Composite Measures• Some concepts are not easily represented by

a single variable– Particularly attitudes and orientations – E.g. religiosity, alienation, prejudice, etc

• Composite measures can help– Can combine information from several variables– Can expand the range of variation– Can be useful for data analysis

Indexes vs. Scales• Both are ordinal measures of variables• Both are composite measures of variables• Indexes are the simple accumulation of scores– “We award a point for each task completed and tally

those scores to create an index value”– “Dow Jones Industrial Index”

• Scales assign scores to patterns of responses– Consider differences in intensity of the response– Have some sort of logical or empirical order– “We assess the health risk to humans of a mix of

pollutants and then award scores on a scale from least to most harmful.”

Indexes vs. Scales• Determine an index measure which would be

contradicted by a scale measure.• For example, if you were to index conservative

politicians by votes on conservative bills, you might incorrectly consider a politician who voted for several moderately conservative bills as more conservative than a politician who did not vote for those bills because they were not conservative enough.

Index Construction• Item selection– What should we include in our index?– Face validity, Unidimensionality, Specificity, Variance

• Examination of empirical relationships– Are variables related to each other? Generally useful.– No relation – probably should not include one– Too close a relation – probably should not include one

• Index Validation– Internal Validation (Item analysis)

• Each item should have independent contribution • Should not be perfectly correlated with other another item

– External Validation • Index should correlate with other presumed indicators of variable• “People who score strongly on the index should score strongly on

other related measures.”

Scale Construction• Bogardus Social Distance Scale

– Determines the willingness of people to participate in social relations of varying degrees of closeness with other kinds of people• (Least extreme)• 1. Are you willing to permit immigrants to live in your country?• 2. Are you willing to permit immigrants to live in your community?• 3. Are you willing to permit immigrants to live in your neighborhood?• 4. Are you willing to permit immigrants to live next door to you?• 5. Would you permit your child to marry an immigrant?• (Most extreme)

– E.g., agreement with item 3 implies agreement with items 1 and 2.• Guttman Scale

– More general case than that above– Binary (Yes/No) responses to a set of questions can be ranked, so that

some one answering yes to a more difficult question will also answer yes to an easier one.

– A coefficient of reproducibility is used as few Guttman Scales are perfect

Scale Construction• Thurstone Scale– Measures intensity structure among indicators by

use of ‘judges’ to assign scores• Likert Scale– Uses standardized response categories in survey

questionnaires to determine the relative intensity of different items

• Semantic Differential– Two opposing possibilities are given and the

respondent selects their gradation between those poles

Scale Construction• Likert Scale

Scale Construction• Semantic Differential Scale

Typology• Classification of observations with respect to

two or more attributes.

Typology of Housing High Quality Low Quality

Pre-War Construction

Post War Construction