For this exercise, your task is to estimate the psychometric properties of a new Cognitive Ability Test. You will need to use SPSS to analyze the data. An SPSS data file is included in the assignment folder, with responses from 252 young adults. Within the data file you will find raw scores for the test items.
To answer each of these questions, run the analyses using SPSS and report relevant information in your write-up (i.e., exact values from the SPSS output). Provide an interpretation of what the results mean. In other words, explain your findings in sufficient detail so that another person could understand what you examined and why. Type your responses using MS Word or Google Docs and upload your responses by clicking on the assignment link.
Difficulty
1. Estimate item difficulty and report the values.
2. How would you describe the difficulty of these items? Are any of them too easy or too difficult? Which ones and why?
Discrimination
3. Estimate the item-total correlations and report the values.
4. How would you describe the discrimination of these items? Do any items differentiate between test takers particularly poorly? Which items and why?
Reliability
5. Compute the internal consistency for the test using the items in the data set and report the value.
6. Explain the impact on the reliability coefficient if each item were deleted.
7. Remove any items that you believe should be excluded from the test based on the information you have evaluated to this point. Compute and report the internal consistency estimate for the test again with any items removed. How did this value change compared with the original internal consistency estimate?