how to use spss for analyzing basic quantitative research ......how to use spss for analyzing basic...
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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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notes! 3
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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