Lesson 1: Introduction to Psychological Testing

A basic idea in classical measurement theory the idea when you measure anything you get a score X- that represent a hypothetical true score plus a certain amount of error (the error can be positive and negative)

To sum that up X= T + E " Score (x) = True Score + Error "

This is true measuring anything psychological or a desk

The very act of measurement always involves error to some extent

True Score- mean of infinite number of estimates.

Standard Error of Measurement (SEM) is standard deviation of error around True Score

Measuring ablility (i.e. aptitude or achievement)
aptitude- learning ability (what your capable of learning)
achievement- refers to crystalized learning (what youve actually learned)

What we know or what we are capable of learning

Have right and wrong answers

Measuring typical patterns of behavior (e.g, personality, clinical issues, attitudes, interests)

Typical performance test do not have right and wrong answers

There is no way of verifying or falsifying the response to a typical performance test. So that is why it is considered no right or wrong anwers.

A) standardized scoring and administration

administrations and scoring are the same for every test.
-standardized opperations for giving it and for scoring it and for interperating scores.

b) use of norms-

(I.e norm sample from which standard scores can be derived from raw scores)

get norm samples and administer the test to the sample and then strastify into age groupsof interests and look at from age groups.


c) use of standard scores

(e.g zscores)

Consistency in measurement. When we say a test is reliable we usually mean it yields the same consistent score time and time again. And all the items internal to the test are measuring the same thing. (internal consistency and consistency overtime)

Whether test is measuring what it is supposed to. if an intelligence test is actually measuring intelligence based on everything we know about intelligence then we would say is is valid.

The simple act of categorization. Categories e.g ethnic groups. Different then form of measurement. Act of measurement but only comparisons are different than.

Units do not clearly defined; rank is implied (e.g., grades A-F; GPA) Greater or less than. Letter grades. Still remains wordinal measurements GPA equal number of A's or B's.

Units are clearly defined; zero is arbituary. (e.g; celsius temperature; z-score) How many untis more or less units greater than or less then but no ration comparison.

Units clearly defined; true zero (e.g. annual salary) zero is referring to the absense of measurment (or what being measured). Can make ratio comparisons (twice as much a third as much)

Measuring constructs- intelligence, depression, things that do not physically exist. Highest scales are intervals (zero is arbituary). Scope of measurement sample: intelligent behavior

Measuring-tangible things rocks, stars things that do physically exist

highes scale is ratio measurment

Scope of measurement- measuring the whole thing the total object.