Populations, samples and variables Flashcards
What is a population?
people in the entire world. Samples should be representative of this
what is a sample?
a subset of a given population
Why do we take samples?
We can’t test everyone so we need to take a sample to infer information about the population
what is ‘cherry picking’?
modifying or subdividing categories in order to get better conclusions
what does a good sample contain?
sub-categories to ensure that the sample reliably represents the population
how should samples be designed?
so that each sub-group can be properly represented in the population
What is a variable?
a set of related events that can take on more than one value
dependant and independant
What is statistical inference?
determining how well a property of one variable can be predicted (inferred) by another variable
what are independent variables?
variables that are predictors
these are the variables that are manipulated
What are dependant variables?
variables that are predicted.
May depend on the IV
What are levels?
different categories within an IV are called levels e.g. vaccinated or not vaccinated
What are control variables?
variables that are kept a constant to prevent influences on the IV and DV
What are the four variable data types?
- nominal
- ordinal
- interval
- ratio
What is nominal data?
data that cannot be ordered or counted e.g. gender, country, occupation
What is ordinal data?
data that can be ordered but cannot be added or subtracted e.g. satisfaction rating from extremely dissatisfied to extremely satisfied.
