214 (2) lecture 2 Flashcards
(23 cards)
What is linear regression?
The simplest form of generalized linear modelling (GLM)
What is the equation for regression when you have 1 IV?
Y= a + bX (+e)
What does the +e stand for in the regression equation?
Error
What are outcome variables?
DVs
What are predictor variables?
IVs
What does linear regression seek to do?
determine how well a model can recreate the data
What does linear regression do?
looks to fit a ‘line of best fit’ through (scatterplot) points
What does linear regression allow us to do?
allows prediction of one variable from another (diff. to correlation)
What does regression assume about variables?
assumes effects of one variable on others is additive: an increase of 1 unit onA leads to a change of X units in B no matter where this change happens
What does regression allow us to predict?
allows us to predict the value of one variable (Y) from the value of another (X)
How does regression allow us to predict?
does this using the line of best fit
What is the line of best . fit?
the linear line that minimizes deviation of each point
What does less deviation (variance) mean for prediction?
More accurate predictions
What information is needed to construct a linear equation?
- Slope
2. Intercept
What is B in the regression equation?
The slope
How do you work out the slope (B)
The change in Y / associated change in X
- requires 2 co-ordinates, the difference between these coordinates is calculated and these are divided.
What is regression weight?
(B) The slope, the amount by which the X value is being weighted in the calculation .
What is Beta?
when X and Y are measured in standard (Z) scores
What are residuals?
Essentially the error
Observed values minus predicted value
The score with the effect of X removed.
How is prediction accuracy assessed?
Looking at variability (sum of squared deviations) - coefficient of determination (R2)
Significance testing - ANOVA, sig result suggests there is a relationship between IV and DV.
What are
SS(Regression) .
and
SS(error)
Regression = R2 error = 1 - R2
How do you conduct regression in SPSS?
Analyze Regression Linear Select DV and IV OK
What are the Intercpet, B (slope) and Beta values in SPSS output?
Intercept = top 'B' column B = bottom 'B' column Beta = beta column
