quant A1

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating

Quantitative and Qualitative Research, third edition

Chapter 6

Collecting Quantitative Data

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

By the end of this chapter,
you should be able to:

• Identify the steps in the process of quantitative data collection.
• Define different approaches used to sample participants for a quantitative study
• Describe the process of obtaining permissions to study individuals and research sites
• List different options for types of data often collected in quantitative research
• Identify how to locate, select, and assess an instrument(s) for use in data collection
• Describe procedures for administering quantitative data collection

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Who Will Be Studied:
Identifying the Unit of Analysis

• Unit of analysis is the level (e.g., individual, family, school, school district) from which the data will be gathered.
• There may be different units of analysis:

One for the dependent variable

One for the independent variable

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Population and Sample

• A population is a group of individuals that have the same characteristic(s).
• A sample is a subgroup of the target population that the researcher plans to study for the purpose of making generalizations about the target population.

Samples are only estimates.

The difference between the sample estimate and the true population is the “sampling error.”

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Populations and Samples

Sample

Target

Population

Sample

Population

- All teachers in high schools in one city

- College students in all community
colleges

- Adult educators in all schools
of education

Sample

- All high school biology teachers

- Students in one community
college

- Adult educators in five schools of
education in the Midwest

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Probability and Nonprobability Sampling

• Probability sampling is the selection of individuals from the population so that they are representative of the population.
• Nonprobability sampling is the selection of participants because they are available, convenient, or represent some characteristic the investigator wants to study.

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Types of Quantitative Sampling

Quantitative Sampling Strategies

Probability Sampling

Nonprobability Sampling

Simple Systematic Stratified Multistage

Random Sampling Sampling Cluster

Sampling Sampling

Convenience Snowball

Sampling Sampling

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Types of Probability Samples

• Simple random: Selecting a sample from the population so all in the population have an equal chance of being selected
• Systematic: Choosing every “nth” individual or site in the population until the desired sample size is achieved

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Types of Probability Samples (cont’d)

• Multistage cluster sampling: A sample chosen in one or two stages because the population is not easily identified or is large
• Stratified sampling: Stratifying the population on a characteristic (e.g., gender) then sampling from each stratum

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Proportional Stratification Sampling Approach

Boys

N=6000

Girls

N=3000

Population

(N=9000)

.66 of pop.

200

.33 of pop.

100

Sample = 300

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Types of Nonprobability Samples

• Convenience sampling: Participants are selected because they are willing and available to be studied.
• Snowball sampling: The researcher asks participants to identify other participants to become members of the sample.

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

What Permissions Are Needed:
Obtaining Permission

• Institutional or organizational (e.g., school district)
• Site-specific (e.g., secondary school)
• Individual participants
• Parents of participants who are not considered adults
• Campus approval (e.g., university or college) and Institutional Review Board (IRB)

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Linking Data Collection
to Variables and Questions

Flow of Activities

Example

Identify the variable

Operationally define the variable

Locate data (measures, observations, documents with questions and scales)

Collect data on instruments yielding numeric scores

Self-efficacy for learning from others

Level of confidence that an individual can learn something by being taught by others

13 items on a self-efficacy attitudinal scale from Bergin (1989)

Scores of each item ranged from 0-10 with 10 being “completely confident”

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Information to Collect:
Types of Data Measures

• An instrument is a tool for measuring, observing, or documenting quantitative data.
• Types of instruments

Performance measures (e.g., test performance)

Attitudinal measures (measures feelings toward educational topics)

Behavioral measures (observations of behavior)

Factual measures (documents, records)

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Locating or Developing an Instrument for Data Collection

• Look in published journal articles
• Run an ERIC search and a descriptor for the instrument you want in an online search to see if there are articles that contain instruments
• Check Tests in Print
• Check Mental Measurements Yearbook published by the Buros Center at the University of Nebraska, Lincoln, NE (http:unl.edu/Buros)
• Develop your own instrument

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Criteria for Choosing a Good Instrument

• Have authors developed the instrument recently?
• Is the instrument widely cited by other authors?
• Are reviews available for the instrument?
• Does the procedure for recording data fit the research questions/hypotheses in your study?
• Does the instrument contain accepted scales of measurement?
• Is there information about the reliability and validity of scores from past uses of the instrument?

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Reliability

• Reliability: Scores from measuring variables that are stable and consistent
• Example: Bathroom scale
• Types of reliability

Test-retest (scores are stable over time)

Alternate forms (equivalence of two instruments)

Alternate forms and test-retest

Inter-rater reliability (similarity in observation of a behavior by two or more individuals)

Internal consistency (consistent scores across the instrument)

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Validity

• Validity: Scores from measuring variables that are meaningful
• Types of validity

Content (representative of all possible questions that could be asked)

Criterion-referenced (scores are a predictor of an outcome or criterion they are expected to predict)

Construct (determination of the significance, meaning, purpose, and use of the scores)

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Scales of Measurement

• Nominal (categorical): Categories that describe traits or characteristics participants can check
• Ordinal (categorical): Participants rank order a characteristic, trait, or attribute
• Interval (continuous): Provides “continuous” response possibilities to questions with assumed equal distance
• Ratio (continuous): A scale with a true zero and equal distances among units

Copyright © 2008 by Pearson Education, Inc. Upper Saddle River, New Jersey 07458 All rights reserved.

John W. Creswell
Educational Research: Planning, Conducting, and Evaluating Quantitative and Qualitative Research, third edition

6.*

Procedures for Administering the Data Collection

• Develop standard written procedures for administering an instrument
• Train researchers to collect observational data
• Obtain permission to collect and use public documents
• Respect individuals and sites during data gathering (ethics)