Lecture 3 Regression Flashcards

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1
Q

Errors are assumed to be…

A

Independent
Normally distributed with a mean of zero
Homoscedastic -

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2
Q

What is the variance explained?

A

How much can be predicted fro the straight line

R^2

Proportion of variance explained = 100%
R^2= 1.00

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3
Q

What does ANOVA tell us? F test

A

Tells us whether the variance explained is significantly different from zero

If it’s not significant, the regression is worthless. Predictor does not explain outcome variable at all.

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4
Q

What can b in regression tell us

A

It is the slope

It can tell us if there’s a relationship between X and y
-Ve if +Ve relationship
Estimate of selected change in y why X increases by 1

If standardised form (z scores) it will be the same as correlation coefficient

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5
Q

What is homoscedasticity and heteroscedasticity?

A

Homo - scatterplot varies equally around the line. Absense of any other pattern rand supports the line…
Hetero - scatterplot against predicted values.

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6
Q

How to write up regression results if
B =.67
Df =88
p

A

b=.67, t(88)=5.03, p

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7
Q

How to write up for ANOVA when
Df = 1 and 88
F = 25.3
p

A

R^2=0.223,F(1,88)=25.3, p

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8
Q

What is the regression model and what is it used for?

A

Y = a + bX + error
Outcome variable = intercept + slope X predictor variable

Want to find a and b which minimises error

Use to find line of best fit for a correlation scatterplot

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