New Uni Quiz Solutions

1. A Multiple Linear Regression Model Summary

   # A tibble: 12 x 5
      term                estimate std.error statistic p.value
      <chr>                  <dbl>     <dbl>     <dbl>   <dbl>
     (Intercept)           7.69     21.1        0.365   0.719
     cyl                   0.877     1.16       0.755   0.459
     disp                 -0.0126    0.0121    -1.04    0.309
     hp                   -0.0234    0.0229    -1.02    0.320
     drat                  0.833     1.69       0.492   0.628
     qsec                  0.276     0.686      0.402   0.692
     gear                  1.94      1.61       1.21    0.242
     carb                 -0.843     0.702     -1.20    0.244
     weight_Low            2.80      3.10       0.905   0.376
     weight_Medium        -0.650     1.71      -0.381   0.707
     transmission_manual   2.13      2.17       0.983   0.337
     engineV-Shaped       -1.12      2.25      -0.497   0.624
   

   
   

   The summary above is from a Multiple Linear Regression model that's used to predict mpg (miles per gallon) for cars based on their 10 features (cyl, disp, etc.). Based on this model summary answer the questions below:
2. Question 1

   2/2

   Assume both you and your friend bought two cars with the exact same features (the features that are included in this model). After purchasing your car, you added one additional cylinder (cyl) to it. What would be the difference in the expected mpg between your and your friend's car according to this model?
3. Question 2

   0/2

   Considering everything else remaining the same, what happens to the expected i.e. predicted mpg with one additional unit increment of horsepower (hp)?

   mpg goes down by about 0.33 miles

   mpg goes down by about 0.02 miles

   Correct answer

   mpg goes up by about 0.02 miles

   Incorrect: mpg doesn't get affected because hp isn't a significant predictor
4. Question 3

   0/1

   If you bought two cars one of Medium weight (weight_Medium) and another of low weight (weight_Low), how the mpg would differ from the same car with High weight? 

   
   

   Note: 

   • There are only three categories of weight class: High, Medium, Low
   • There are multiple correct answers and points will be deducted for choosing wrong answer(s)

   Partial and negative credit

   Points may have been deducted for incorrect answers.

   Incorrect: On average, the low-weight car would have 2.8 miles higher mpg compared to the medium-weight car

   On average, the medium-weight car would have 0.65 miles lower mpg than the high-weight car

   Correct answer

   On average, the high-weight car would have 2.8 miles lower mpg compared to the low-weight car

   Correct answer

   On average, the medium-weight car would have 0.65 miles lower mpg than the low-weight car
5. Question 4

   0/1

   What is the predicted mpg for a car with the following features:

   • 6 cylinders
   • 160 disp
   • 110 horse power
   • 3.9 drat
   • 16.46 qsec
   • 4 gears
   • 4 carb
   • Medium weight
   • Manual transmission
   • V-Shaped engine

   
   

   Note: 

   • Answer format: use the number up to 2 decimal points without rounding e.g. for a value of 10.9568 use 10.95

   Your Answer:

   Incorrect

   The answer is 20.9.

6. Fit a Logistic Regression to predict the probability of heart disease 

   
   

   Run the following line of code to get the dataset: 

   heart_disease <- read.csv('https://www.statlearning.com/s/Heart.csv')[,-1]
   

   
   

   Now complete the following steps to answer questions below:

   1. Set 99 as your random seed i.e. run this function: set.seed(99) 
   2. Split the dataset to get 80% of the records as training data and 20% for testing
   3. Fit a Logit Model to predict the probability of heart disease (AHD) based on these factors: Age, Thal, RestBP, Chol, Fbs, RestECG, Ca
   4. We use plus sign to add multiple specific predictors to fit() function. Check the example code below where predictor01 and predictor02 are used to predict the outcome: 

   fit(outcome ~ predictor01 + predictor02, data = example_data)
   
7. Question 5

   2/2

   Based on the coefficient values for the Thal levels, which of the following statements can are true?

   
   

   What is the difference in odds of having AHD between a patient with Normal Thal reading and a patient with Fixed Thal reading but otherwise with the same health condition?

   The odds of having AHD for the patient with Reversable Thal is about 1.62 times the odds of having AHD for the patient with Fixed Thal considering they have the same health condition otherwise 

   The odds of having AHD for the patient with Normal Thal is about 0.13 times the odds of having AHD for the patient with Fixed Thal considering they have same health condition otherwise 

   Patients with Reversable Thal have the highest odds when compared with other patients with Normal and Fixed Thal considering they are of same health condition otherwise.

   Correct: All are correct

   Correct answer
8. Question 6

   0/2

   All else being equal, the odds of AHD multiplies by how much with one additional unit increment in RestECG? 

   
   

   Answer format: use the number up to 2 decimal points without rounding e.g. for a value of 10.9568 use 10.95

   Your Answer: 1.00

   Incorrect

   The answer is 1.62.
9. Question 7

   0/2

   A 61 year old patient's odds of having AHD are very slightly lower than the odds of a 60 year old patient's odds of having AHD assuming their health condition is the same otherwise.

   T

   TrueCorrect answer

   F

   Incorrect: False

Your Answers:

Results for question 1.

1

0 / 25 points

Another name for risk alternatives is ________.

Incorrect answer:

Risk Responses

Correct Answer:responses, response

Results for question 2.

2

0 / 25 points

Comparing alternatives in expert interviews is often used on the _________ stage. 

Incorrect answer:

Risk Assessment

Correct Answer:data-gathering, data gathering

Results for question 3.

3

0 / 25 points

_________alternatives are a by-product of the expected monetary value technique. 

Incorrect answer:

Risk Response

Correct Answer:decisions, decision

Results for question 4.

4

0 / 25 points

In situations where risks seem insurmountable, alternatives can sometimes be found in examining the ________rather than the sources of risk.

Incorrect answer:

consequences

Correct Answer:outcomes, outcome