Exam 1 Flashcards
Meaning of psychometrics
Psycho: breath, spirit, soul (greek root)
Metric: measure, size, distance (greek root)
Importance of studying measurement (5 reasons)
Minimize subjectivity of judgment
Make more precise statements
Quantify your observations
Can never be sure that measurement is perfect
Assess the degree of error (measurement itself can cause error and participant/researchers can introduce bias)
Our first test done
Hospital when we are born
Apgar test
5 categories with a score ranging from 0-2 (Appearance, pulse, grimace, activity, respiration)
7-10 is a normal score
Empirical thinking
Knowledge that isn’t based on the bible
Will lead to truth
Francis Galton
Founder of psychometrics
Obsessed with observations and measurements
Degree of association between 2 elements (Pearson’s R, correlation)
Recognition of individual differences: understanding the ways in which people differ, how do we calculate those differences, what causes those differences
2 types of individual differences
Trait differences
State differences
Trait differences
Resistant to change over time
Refers to behavior in general
Often easier to measure with questionnaires
Ex: extraversion, IQ, depression, anxiety
State differences
Subject to change over a short period of time
Refers to behavior at the moment
Easy to measure with tasks and questionnaires
Ex: sleepiness, hunger, depression, anxiety
Why we study psychometrics
Ensure reliable and valid measures
Application
Questionnaires are good
Ensure reliable and valid measures
Essential to sound science
How else can we identify individual or cultural differences
How else can we assess traits
Application
Good judgments require good measures
Questionnaires are good
They make good dependent variables
Help eliminate errors as covariates, controls, or experimental groups
Methods of measurements
Stimulus-centered scaling: psychophysics, the relation of physical, directly measurable, stimuli to perception (ex: sound perception)
Subject-centered scaling: estimating the subjective presence, absence, or degree of a construct
Levels of measurement
Nominal
Ordinal
Interval
Ratio
Nominal
Numbers are assigned as labels only, doesn’t mean anything
Numbers could easily be words
Ex: coding sex with numbers
Ordinal
Numbers are not only to label, they rank individuals
Use numbers in a meaningful way
Degree of change isn’t fixed between numbers
Ex: ranking of height between individuals
Interval
Numbers are labels, reflect ranks, and tell us exactly how much more of something we have now
No true zero
Ex: temperature scale
Ratio
Numbers are labels, reflect ranks, tell us exactly how much more of something we have now, and we have a true zero
Numbers can’t be negative
Distribution of data
Normal distribution