SPRING Questionnaire Analysis Flashcards
what is item analysis
looking for large item variance to show a difference
- removal of poor questions to ensure validity
what analysis uses descriptive Qs
chi square
ie count score/categorical variables
what analysis uses analytic Qs
correlational
what is internal validity
pproximate truth about inferences regarding cause-effect or causal relationships - NOT OBSERVATIONAL OR DESCRIPTIVE
whether observed changes can be attributed to your program or intervention (i.e., the cause) and not to other possible causes
each q = item
item analysis- remove items not measuring a concept
aim to gain internal consistency
how to test for internal validity
check for sufficient variance for each item ie differences between people
check if any items show bimodal distribution
how well does each item correlate with the total score on the concept/construct
how well to the items intercorrelate
do the items correlate but not measure construct?
define bimodal distribution
do the questions identify distinct groups
ie two seperate average answers - need items to discriminate between high and low respondents
what does poor interitem validity cause
poor reliability
how might the items correlate but not measure the construct of interest
too much variance
poor validity - not measure the entire construct
test for item total correlation
cronbachs alpha
Calculate correlation between total scores on each item of the test and the total score on test/subtest
how many contructs can you do an inter item analysis on at any one time
1 analysis per construct
Interpreting inter-item correlations
Keep items that show good correlation with other items
Items with poor inter-item correlations should be removed
Each time an item is removed > recheck inter-item correlations - Each time an item is removed it can impact on correlations between other items
what is a good inter item correlation
anything below 0.3 = weak correlation - keeps items with good correlations and remove poor
what is a good cronbachs alpha inter-total correlation level
gives value 0-1
alpha
