S1 Wk 3 - Variables and Measurement Flashcards
what is a variable
things we are trying to control and measure
anything that varies between people, over time within context
variables are …….. and can be used ………
related to one another
to predict one another
what is random variations
sometimes called noise or error
means that individuals vary naturally
what is an independent variable
value that is fixed or controlled and NOT dependent on something else in our study
what are the levels of the IV
the conditions or groups used in a study
what is the dependent variable
depends on something else
something we think is affected by another variable
what is between subjects
comparing different groups of people
independent measures
what is within subjects
compares same ppts across different groups
repeated measures
what is an experiment
involves manipulating the IV
what is interval data
measurements with an equal interval between each point on the scale
can be + or -
e.g. temp, time of day, date in years, money in bank account
what is ratio data
measurements with an equal interval between
mathematically meaningful absolute zero
e.g. height, weight, money in pocket
what does SPSS refer to interval and ratio as
scale
what is discrete data
can be counted in whole numbers
subdivision of the values doesn’t make sense
what is continuous data
Variable is continuous if it can be subdivided further
what type of data are ratio and interval usually
continuous
what type of data do parametric tests use
interval or ratio data
what type of data do non-parametric tests use
ordinal or nominal
What does parametric mean
Refers to the setting of parameters required to be able to compare data to the model
What does internal validity mean
Are the study’s conclusions Justified by the evidence presented
What does reliable mean
Consistent; tells us the same thing over time
What does valid mean
Actually measures what it’s supposed to measure
how do we calculate variance and standard deviation
find the mean
for each data point, minus the mean and square it
sum the values from step 2
divide the by the number of data points (-1 maybe)
square root for the standard deviation
what is normal distribution
Normal variation, some low scorers, some high scorers, most people fall in the middle of the scale
what is the variance
how far away individual scores are from the parameters such as the mean
