Exam 1

1. Metainformation

   Tag	Value
   file	Reliability_eur-reliability-208-en_eur-reliability-208-en
   name	eur-reliability-208-en
   section	Reliability/Analysis/Cronbach's alpha
   type	schoice
   solution	FALSE, FALSE, TRUE, FALSE
   Type	Calculate
   Program	Calculator
   Language	English
   Level	Statistical Literacy

   Question

   Below you see the variance-covariance matrix of three variables (V1 to V3). Calculate Cronbach’s alpha:

   Variable	V1	V2	V3
   V1	332
   V2	165	545
   V3	159	235	336

   Use the formula:

   $Cronbach's Alpha = (k / (k-1)) \times ∑C_{ij} / S^2_x$

   
   
   1. FALSE: .21
   2. FALSE: .47
   3. TRUE: .72
   4. FALSE: .78
   
   

   Solution

   We calculate the sum of the covariance and double it: $2 \times (165+159+235)=2 \times 559=1118$. For the variance of the total score we add the item variances: $1118+332+545+336=2331$. Cronbach’s alpha then becomes: $3 \div 2 \times 1118 \div 2331=.72$

   
   
   1. False
   2. False
   3. True
   4. False