logistic regression Flashcards

1
Q

DV in logistic regression is what type of variable

A

binary

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2
Q

baseline model predicts what

A

most common occurrence not what value we after

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3
Q

categorical variable is from the model which is

A

small number of possibel outcomes

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4
Q

values of logstic vs linear regression

A

logsitic = between 0 and 1
linear = infinity- negativr infinity

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5
Q

if linear regression y = 0 logstic will =

A

0.5

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6
Q

higher thann 0 in linear regression = in logsitic regression

A

greater than 0.5

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7
Q

in the form of a prediction if linear regression y> 0 logstic =

A

1

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8
Q

logsitic is non linear how to make it back to linear regression

A

use odds

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9
Q

although y value is 0 or 1 outcome variable output will be

A

probabaility between 0 and 1, output is a probaility not 0 or 1 but between them

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10
Q

when we build logistic regression model y will take value of 0 or 1 but outcome variable will be

A

continuos score/ probability between 1 or 0

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11
Q

output is

A

probability not or 1 but between them

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12
Q

create model using what set and evaluate on what set

A

training, testing

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13
Q

selecting a threshold of 0.5 predicts

A

most likley outcome

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14
Q

ROC helps us and what are its axis

A

pick threshold, TP rate or sensitivity on y axis, TN or specificity on x axis

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15
Q

ROC captures

A

all thresholds simultaneously

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16
Q

high thresholds have

A

high speceficty and low sensitivty

17
Q

low thresholds have

A

low speceficty and high sesnsitivty

18
Q

2 main ways to evaluate the model

A

AUC and accuracy

19
Q

what are some issues with accuracy, sensitivity, and specificity

A

depend on the threshold

20
Q

AUC is area under curve what is the interpratation

A

given a random positive and negative proportion of the time you can guess which is correct.

21
Q

AUC is less effected by what then accuracy

A

sample balance

22
Q

maximum of AUC

A

1 perfect prediction: your false positive rate is zero, sensitivity goes up to 1 without compromise on FP rate

23
Q

Minimum AUC

A

0.5 -> just guessing

24
Q

when deciding which model is best use

A

accuracy, senssitivy and speceficty. caculate gains and losses from model to the baseline model

25
Q

in the box plot is prediciting

A

avergae scores for patient not probability