Introduction to Psychometrics
Before we dive into the commonly confused words, let’s have a quick introduction to psychometrics. It is the field of study that focuses on the measurement of psychological attributes, such as intelligence or personality, through the use of tests and assessments.
1. Reliability vs. Validity
Reliability refers to the consistency of a measurement, while validity refers to the accuracy or truthfulness of a measurement. In simple terms, reliability is about getting consistent results, and validity is about getting the right results.
2. Norm-Referenced vs. Criterion-Referenced
Norm-referenced tests compare an individual’s performance to a group, providing information on how they rank. Criterion-referenced tests, on the other hand, assess whether an individual has achieved a specific level of knowledge or skill.
3. Item vs. Test
An item is a single question or task within a test, while a test is a collection of items. So, think of it this way: an item is like a puzzle piece, and a test is the complete puzzle.
4. Raw Score vs. Standard Score
A raw score is the unadjusted score a person receives on a test, while a standard score is a transformed score that allows for comparison across different tests or populations.
5. Formative vs. Summative Assessment
Formative assessments are used during the learning process to provide feedback and guide instruction. Summative assessments, on the other hand, are used to evaluate learning at the end of a unit or course.
6. Speed vs. Power Test
Speed tests assess how quickly a person can complete tasks, while power tests focus on the level of difficulty of the tasks, regardless of time constraints.
7. Construct vs. Criterion-Related Validity
Construct validity refers to how well a test measures the theoretical construct it is intended to measure. Criterion-related validity, on the other hand, is about how well a test predicts or correlates with a specific criterion.
8. Item Difficulty vs. Item Discrimination
Item difficulty is a measure of how many people answer an item correctly. Item discrimination, on the other hand, assesses how well an item differentiates between high and low performers.
9. True Score vs. Observed Score
The true score is the hypothetical score a person would receive if there were no measurement error. The observed score, however, is the actual score obtained, which may be influenced by measurement error.
10. Test-Retest Reliability vs. Parallel Forms Reliability
Test-retest reliability assesses the consistency of a test by administering it to the same group of individuals at two different times. Parallel forms reliability, on the other hand, compares the results of two different but equivalent forms of a test.