L15 - Correlation Flashcards
what is correlation
correlation is when two variables are linked to one another and rise and fall together
what is Causeation?
Causation is when one variable creates a change in another variable.
what does a positive and negative correlation mean.
a positive correlations refers to two variables that rise and fall together due. A negative correlation between two variables has one variable rise as one falls.
what are the four criteria for inferring causality
- temporal ordering
- correlation
- causal mechanism
- rule out confounds
what is temporal ordering? in terms of determining causality.
hypothesized cause might come before an affect.
what is correlation? in terms of determining causality.
do the variables have a strong correlation.
what is Casual mechanism? in terms of determining causality.
the plausible story relating how the two variables are linked.
what does ruling out Confounds mean in terms of determining causeality
it refers to making sure there are no other variables that are potentially responsible for the correlation.
What does an r value represent? and what does an r value of 0 represent?
An r value is a measure of the correlation between datasets. a correlation of 0 means that the two datasets are not related in anyway.
What is Covariance?
Covariance shows you how two variables differ from one another. opposite of correlation.
What is Pearson’s r?
Pearson’s r value is used to standardize the interpretation of covariance by dividing it by the standard deviations of the two samples.
what are the assumptions that need to be met in order to calculate pearsons r?
- data are interval or ratio
- the variables have linear relationships
- the variables are normally distributed
- the data come from a random sample
what is the range of pearsons r value? and what do they mean?
-1 to 1.
with -1 having a strong negative correlation and 1 having a strong positive correlation. 0 means there is no correlation.
