Chapter 4 - Correlation Flashcards
what are scatter diagrtams used for
to represent the relationship between two variables
what are strong correlations
data where the points on a scatter diagram are all very close to the regression line
what are weak correlations
data where the points on a scatter diagram are all fairly far from the regression line
what are positive correlations
when one variable increases, the other also increases
what are negative correlations
when one variable increases the other decreases
what is the regression line
the perfect line of best fit
a line on a scatter diagram where the total distance from each point to the line squared is the lowest value possible
what does the y intercept of a regression line represent
the minimum y value when the x value is 0
what does the gradient of a regression line represent
the change in the y value when the x value changed by one
what is a causal relationship between variables
when one variable directly causes another
remember that correlation is not equal to causation
give 2 limitations of models using regression lines
you cannot extrapolate data to predict results outside of the data range
you can only used the x value to find the y value
what variables are plotted on the axis
the IV is usually on the x axis
the DV is usually on the y axis
what is extrapolation
predicting data outside of the measured data range
