final exam Flashcards
correlation (r)
reflects the strength and direction of a relation between two continuous variables
When are correlations stronger?
They can be from 1 to -1, correlations closer to 1 are stronger than correlations closer to 0
What do negative correlations tell us?
the variables have a different relation between them than positive correlations
Examples of correlations
strong - r= .80
weak- r=. 10
positive- r= .80, .10
negative- r= -.80, -.10
Correlation does not mean what?
Causation
regression coefficient (b)
reflects how well one of those continuous variables predicts the other
predict
means we can see what happens with one variable and predict what will happen with the other
Regression equation
y= a + b (x)
What do the variables mean in regression equation?
x= predictor variable
y= criterion variable (score we are predicting)
b= regression coefficient
a= regression constant (where we start)
b in the formula means
for every 1 raw unit increase in x their is a b unit increase in y
a in the formula means
the predicted value of y when x equals zero
conceptual interpretation
For every one raw unit increase in [x -> hours slept last night] there is a [b -> 1] unit increase in [y -> happy mood]
Substantive interpretation
For every additional hour of sleep people are predicted to be one point happier
multiple regression
more than one predictor
Does income and sleep predict happiness?
simple regression
one predictor
Does income predict happiness?
multiple regression equation
y= a + b(1)x(1) + b(2)x(2) and so on depending on how many predictors
b 1.2
partial regression coefficient for X1
b 2.1
partial regression coefficient for X2
partial out
to remove shared credit from other predictions
conceptual interpretation for partial regression
for every raw unit increase in X there is a b 1.2 unit increase in Y partialing out the other predictions.