Basics Flashcards
What are odds?
Odds are the ratio of an event happening to event not happening
What is probability?
Probability is the ratio of number of times an event happens to the number of times that an event happens or does not happen. Range[0,1]
How can we get odds from probabilities?
odds of success = p/(1-p)
where p is probability of success
For odds, what is the range of success and fail?
Losing range is [0,1]
Winning range is [1, infinity]
Why do we convert to log(odds)
To make the range of winning and losing symmetric
What is logit function?
log(p/1-p)
i.e. log of the ratio of probabilities
What is odds ratio?
It ratio of two odds. As in the case of odds, the range is [0,1] and [1,infinity]
Hence, log(odds ratio) makes sense
What is R-Square and Adjusted R-Square?
It is used to evaluate the goodness of fit of a regression model.
They provide information about how well the independent variables explain the variability of the dependent variable.
What is the R-square equation?
R2 = ( Var(mean) - Var(fit) ) / Var(mean)
r2$ of dependent is explained by the predictor
What is the difference in adjusted R-Square?
Adjusted R-square penalizes for addition of unnecessary variables.
What is the equation for adjusted R-square?
1 - ((1-R2)(n-1)/(n-k-1))
