PSYC217 Chapter 5 - Measurement Intro Self-Report Measures - Operationalizations are the specific methods used to manipulate or measure a variable Reliability - A reliable measure is consistent - Reliability and validity are important characteristics of all operationalizations - Systematic research on reliability and validity is often carried out on self-report measures of individual differences. - Psychologists use self-report measures to study a wide variety of topics, including attitudes, evaluations, motivations, and preferences. · Self-report measures are often used to study personality traits (relatively stable tendencies in how people think and feel) · Five broad personality traits: openness to experience, conscientiousness, extraversion, agreeableness, and neuroticism (often labelled as its inverse, emotional stability). - One of the most important aspects of a good operationalization is reliability > refers to the consistency or stability of a measure. " Reliability: degree to which a measure is consistent, providing a stable form of measurement. " A highly reliable measure will give you about the same result, every time you use it to measure the same thing. " If you're measuring the same object, then it should give you the same estimate of length, and we would then consider this to be a reliable measurement. - A highly reliable measure of a stable psychological variable (e.g., conscientiousness) will yield about the same result each time you administer the test to the same person. · E.g., a test would be unreliable if it found someone to have an average level of conscientiousness first, then a low level second, then a high level third. · A reliable measure does not fluctuate much from one measurement instance to the next when measuring the same thing. · Fluctuations in measurement can be attributed to error in the measurement tool. · All measures have some error -> no measure is free of faults in scores. - A formal way to understand reliability involves two concepts: true score and measurement error 1. True score -> the person's actual level of the variable of interest " True score: An individual's actual level of the variable being measured, not to be confused with the score they get on the measure of that variable. · Not the score they get on the measure of that variable) 2. Measurement error -> any contributor to a measure's score that is not based on the actual level of the variable of interest (i.e., not the true score). " Anything that contributes to the score on a measure not based on the true score. · Responsible for the degree to which a score on a measure deviate from the true value of the measured variable. - EXAMPLE: measuring how quickly people can react to a stimulus (i.e., reaction time) > must press a button on a keyboard as soon as they hear a tone.
. Reaction time is calculated by the milliseconds it takes from onset of the tone till people press a button > time between tone and button-press, is determined by reaction speed. " Other factors