Item Analysis and Norms

Review Quiz 2b


Criterion Referenced Tests

Internal Consistency

Preliminary Analysis

Item Difficulty (p)

Formula for p

Item Discrimination (D)

Item Discrimination Formula

Example 1

Determine Frequency of each response

Determine Total Correct Responses for each Test Taker

Find High, Middle, and Low Scores

Use High and Low groups for p and D calculations.

Item 1 Difficulty (p)

Formula for p (item 1)

Item  1 Discrimination Formula


Factors Affecting Items

Analysis of Distracters

Item Characteristics Curve

Plot Total Correct Responses against Proportion Correct for item

Example 2




Purpose of Norms

Norm verses Criterion

Sampling for Norms

Simple Random Sample

Stratified Random Sample

Cluster Sampling

Item Sampling

Evaluating Norms

Types of Norm Scores

Percentile Norms

Steps in Calculating Percentile Ranks

Standard Score z

Calculating z scores

Z scores

Normalized Standard Scores

Calculating zn

Calculating T

Calculating NCE