Have you always been struggling with SPSS? Look no further! This document can help you out, as it includes a comprehensive overview of SPSS techniques used within the field of psychometrics. The summary is written in the format of an instruction manual and thus contains clear and straight-forward ...
Institution: Leiden University
Course: Psychometrics
,Content
1. Scaling and norming test scores .................................................................................................... 4
1.1 Scale score ................................................................................................................................. 4
1.2 Report scale scores ................................................................................................................... 4
1.3 Normed scale scores ................................................................................................................. 4
1.4 Norm table ................................................................................................................................... 5
2. Reliability ........................................................................................................................................... 6
2.1 Split-Half method........................................................................................................................ 6
2.2 Cronbach’s Alpha ....................................................................................................................... 6
3. Validity................................................................................................................................................ 7
3.1 MultiTrait-MultiMethod matrix ................................................................................................... 7
3.2 Total scores................................................................................................................................. 7
3.3 Correlation table ......................................................................................................................... 7
4. Construct Validity & Principal Component Analysis .................................................................... 9
4.1 Data inspection for PCA ............................................................................................................ 9
4.2 Performing PCA ......................................................................................................................... 9
4.2a PCA without rotation of axes .............................................................................................. 9
4.2b PCA with rotation of the axes ........................................................................................... 10
4.3 How many components? ........................................................................................................ 10
4.4 Explained variance total and per variable ............................................................................ 10
4.4a Communalities .................................................................................................................... 10
4.4b Eigenvalue greater than 1 ................................................................................................ 10
4.5 Component plot ........................................................................................................................ 10
4.6 Interpretation Components ..................................................................................................... 11
5. Item Response Theory .................................................................................................................. 12
5.1 Proportion / difficulty score ..................................................................................................... 12
5.2 Ability.......................................................................................................................................... 12
5.3 Relation difficulty & ability ....................................................................................................... 12
6. Test bias .......................................................................................................................................... 13
6.1 Centering test scores............................................................................................................... 13
6.2 Scatterplot: Criterion & Test scores ...................................................................................... 13
6.3 Dummy variable ....................................................................................................................... 14
6.4 Interaction variable................................................................................................................... 14
6.6 Intercept and slope coefficient ............................................................................................... 14
7. Discriminant Analysis..................................................................................................................... 15
2
,7.1 Summary Data & group Distribution...................................................................................... 15
7.2 ANOVA ...................................................................................................................................... 15
7.3 Preconditions/assumptions for DA ........................................................................................ 15
7.4 Matrix plot .................................................................................................................................. 15
7.5 Discriminant Analysis .............................................................................................................. 15
7.5b Predictive DA .......................................................................................................................... 16
7.6 Classification by means of Pythagoras Theorem................................................................ 16
3
, 1. Scaling and norming test scores
1.1 Scale score
Calculate scale scores by means of finding the mean of the items concerned:
Mean.n:
- n is the number of items the participant should at least have answered and which
may thus not contain a missing value
- Used to not lose too much of your data due to missing values
Analyze > Descriptive Statistics > Descriptives > OK
- Click save standardized values as variables
- Variables: Select variables concerned
- Options: unclick the boxes (not necessary)
Characteristics z-scores:
- SD=1
- Mean=0
- Negative: below the mean
- Positive: above the mean
- How to check whether z-scores are accurate:
Descriptive statistics > Descriptives > OK
- Variable: z-scores concerned
- Options: mean (0 in output?), sd (1 in output?), min&max
- Unclick save standardized values as variables
• T-scores:
Transform > Compute variable > OK
- Target variable: name variable (e.g.: Tlokfa_EN)
4
Voordelen van het kopen van samenvattingen bij Stuvia op een rij:
Verzekerd van kwaliteit door reviews
Stuvia-klanten hebben meer dan 700.000 samenvattingen beoordeeld. Zo weet je zeker dat je de beste documenten koopt!
Snel en makkelijk kopen
Je betaalt supersnel en eenmalig met iDeal, creditcard of Stuvia-tegoed voor de samenvatting. Zonder lidmaatschap.
Focus op de essentie
Samenvattingen worden geschreven voor en door anderen. Daarom zijn de samenvattingen altijd betrouwbaar en actueel. Zo kom je snel tot de kern!
Veelgestelde vragen
Wat krijg ik als ik dit document koop?
Je krijgt een PDF, die direct beschikbaar is na je aankoop. Het gekochte document is altijd, overal en oneindig toegankelijk via je profiel.
Tevredenheidsgarantie: hoe werkt dat?
Onze tevredenheidsgarantie zorgt ervoor dat je altijd een studiedocument vindt dat goed bij je past. Je vult een formulier in en onze klantenservice regelt de rest.
Van wie koop ik deze samenvatting?
Stuvia is een marktplaats, je koop dit document dus niet van ons, maar van verkoper Hannah_Bakker. Stuvia faciliteert de betaling aan de verkoper.
Zit ik meteen vast aan een abonnement?
Nee, je koopt alleen deze samenvatting voor €4,99. Je zit daarna nergens aan vast.
