How To Use SPSS For Analyzing Basic Quantitative

Research QuestionsSUMMER INSTITUTE, 2016

Steven A. HechtMaria R. Ligas

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TODAY WE WILL: • Discuss how to get SPSS – rent it!

• Go over basics of SPSS

• Go over some popular analyses based on following examples of research questions:

1. Was there significant improvement in reading scores between pretest and posttest?

2. Were there significant differences between groups in reading scores?

3. Were there significant differences between groups in Posttest reading scores while controlling for initial Pretested ability?

4. Did group, pretested ability, and estimate IQ all uniquely predict Posttest reading scores?

• Discuss YOUR OWN research questions.2

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GET IBM SPSS

• You can rent SPSS.

• Different options depending on the

analysis you want to do and how long

you plan to use IBM SPSS

• http://www.onthehub.com/spss/

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SPSS DATA FILE (.SAV) HAS TWO SCREENS

• Data view

• The place to enter data

• Columns: variables

• Rows: records

• Variable view

• The place to enter variables

• List of all variables

• Characteristics of all variables5

BEFORE THE DATA ENTRY

• You need a code book/scoring guide

• You give ID number for each case

(NOT real identification numbers of

your subjects) if you use paper survey.

• If you use online survey, you need

something to identify your cases.

• You also can use Excel to do data entry. 6

ENTER DATA IN SPSS

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Columns:variables

Rows: cases

Data View Tab

ENTER VARIABLES

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Under Variable

View

ENTER VARIABLES

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2. Type variable

name

3. Type: numeric or

string

4. Description of variable

ENTER VALUE LABELS FOR VARIABLES IF NEEDED

Based on your code

book!

ENTER DATA FOR YOUR CASES

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Under Data View

IMPORT DATA FROMEXCEL!

• Select File Open Data

• Choose Excel as file type

• Select the file you want to import

• Then click ok

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CLEAN DATA AFTER IMPORT DATA FILES

• Key in values and labels for each variable

• Run frequency for each variable

• Check outputs to see if you have variables with wrong values.

• Check missing values and physical surveys if you use paper surveys, and make sure they are really missing.

• Sometimes, you need to recode string variables into numeric variables

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RESEARCH QUESTION #1:

Was there significant improvement in reading scores for the same students between pretest and posttest?

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PretestReading Scores

Posttest Reading Scores

• So, were the average reading scores different between

pretest and posttest?

• Use the paired sample t-test

Intervention or Treatment

PAIRED SAMPLE T-TEST

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• Analyze -> compare means -> paired sample t-test

PAIRED SAMPLE T-TEST

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• Analyze -> compare means -> paired sample t-test

SPSS Output file (.spv)

PAIRED SAMPLE T-TEST

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• Analyze -> compare means -> paired sample t-test

SPSS Output

If the value is .05 or smaller, then the

difference is statistically significant!

RESEARCH QUESTION #2: Were there significant differences between two independent groups in math scores?

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Groups (IV)

(Control vs.

Treatment)

DVReading scores

• So, were the average reading scores different between Control Group and Treatment Group?• You could use a t-test or Analysis of Variance. Lets use

ANOVA

ANALYSIS OF VARIANCE

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• Analyze -> general linear model -> univariate

ANALYSIS OF VARIANCE

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• Analyze -> general linear model -> univariate

Here is your predictor

If this value is .05 or less then effect is statistically significant

RESEARCH QUESTION #3:

Were there significant differences between groups in posttest reading scores while controlling for initial pretested ability?

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IVGroups (control versus

treatment)

DVPosttest Reading

• You could use Analysis of Variance with a covariate

CovariatePretest

Reading

ANALYSIS OF VARIANCE WITH A COVARIATE

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• Analyze -> general linear model -> univariate

ANALYSIS OF VARIANCE WITH A COVARIATE

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• Analyze -> general linear model -> univariate

Here is group

predictor

If this value is .05 or less then effect is statistically significant

covariate used to look at

change in reading

RESEARCH QUESTION #4:

Did group, pretested ability, and estimate IQ all uniquely predict posttest reading scores?

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IVGroups

DVPosttest Reading

• You could use Analysis of Variance or REGRESSION

CovariatePretest

Reading

CovariateIQ

REGRESSION

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• Analyze -> Regression-> Linear

REGRESSION

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• Analyze -> regression-> linear

Here is Group

predictor

Look! Group is no longer significant!

covariate used to look at

change in reading

covariate used to

control for IQ

WHY DID WE SHOW YOU REGRESSION?

Useful when we do not have groups, but instead have several predictors of an

outcome

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Letter Knowledge Posttest

Reading

Pretest Reading

IQ

Motivation Vocabulary

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notes! 28

- What research questions do you have?- What kind of statistical analysis would be appropriate?

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