Week 3 Reading Flashcards
Discovering Stats text, 1.6, 18.9, 18.10, 18.11, 18.2
level of measurement
the relationship between what is being measured and the numbers which represent what is being measured.
categorical variable
made up of categories.
nominal variable
when two things are equivalent in some sense and given the same name, but there are more than 2 possibilities
binary variable
when just two distinct types of things can exist, in all cases there are just two categories, and an entity can be placed into only one of two categories.
ordinal variable
When categories are ordered.
Continuous variable
gives us a score for each person and can take on any value on the measurement scale that we are using.
Interval variable
“considerably more useful than ordinal data”, must be certain that equal intervals on the scale represent equal differences in the property being measured.
A truly ___ variable can be measured at any level of precision.
Continuous
discrete variable
can take on only certain values (usually whole numbers) on a scale.
Measurement error
the common discrepancy between the numbers we use to represent the thing we’re measuring, and the actual value of the thing we’re measuring.
We can ensure that measurement error is kept to a minimum by determining properties of the measure that give us confidence that it is doing its job properly. Two of these properties are-
validity and reliability.
Criterion validity
Whether you can establish than an instrument measures what it claims to through comparison to objective criteria.
Concurrent validity
can be assessed when data is recorded simultaneously using the new instrument and existing criteria.
Predictive validity
assed when data from the new instrument is used to predict observations at a later time.
