lecture 4 - regression Flashcards
what do regression tests look at?
whether x influences y
an effect
what are the 3 different terms for x?
- independent
- explanatory
- predictor
what are the 3 different terms for y?
- dependent
- outcome
- criterion
which axis is the x variable always on?
horizontal
which axis is the y variable always on?
vertical
what is the simplified regression equation?
y = a+bx
a =
intercept (where the line on the graph starts)
b =
the slope
this is the coefficient
tells us how much y changes by with one unit change in x
the larger the value of b…
the steeper the line
if b = 0 the line is…?
flat
y = a+bx is the equation for?
a straight line
simplified regression equation
OLS regression
- works out error
- shows the best place for the line of best fit according to the least amount of error
what does OLS stand for?
ordinary least amount of squares
what is error also referred to as?
residual
what are the 2 most important elements to consider when assessing b?
- direction and size
2. statistical significance
what is the extended equation with OLS regression?
y = a + bx + u
what does u stand for in the extended regression equation?
error
what is the value of R squared always between?
1 and 0
- 1 is the perfect model and explains the data exactly
- 0 is doing nothing to explain the data
is R squared a proportion?
yes - e.g. if it = 0.4, this means it explains 40% of the variance in Y with our X
