100% satisfaction guarantee Immediately available after payment Both online and in PDF No strings attached
logo-home
Previously searched by you
Previously searched by you
logo
ISYE /2024 MIDTERM 2 QUESTIONS AND CORRECT ANSWERS | VERIFIED | GRADED A+ $12.49
Add to cart
Quickly navigate to
Preview
  2.  
  3. ISYE 6501
  4.  
  5. ISYE 6501

Exam (elaborations)

ISYE /2024 MIDTERM 2 QUESTIONS AND CORRECT ANSWERS | VERIFIED | GRADED A+

1 review
 18 views  0 purchase
  • Course
  • ISYE 6501
  • Institution
  • ISYE 6501

ISYE /2024 MIDTERM 2 QUESTIONS AND CORRECT ANSWERS | VERIFIED | GRADED A+

Preview 3 out of 21  pages

Document information

  • June 26, 2024
  • 21
  • 2023/2024
  • Exam (elaborations)
  • Questions & answers

Subjects

Written for

  • ISYE 6501
  • ISYE 6501

1  review

review-writer-avatar

By: RegisteredNurse • 4 months ago

Very Informative, detailed and timely, I passed, thank you very much

Seller

avatar-seller
DrBellaPhD

Reviews received

Content preview

ISYE 6501 2023/2024 MIDTERM 2 QUESTIONS AND CORRECT ANSWERS | VERIFIED | GRADED A+ 1.when might overfitting occur when the # of factors is close to or larger than the # of data points causing the model to potentially fit too closely to random effects 2.Why are simple models better than complex ones less data is required; less chance of insignificant factors and easier to interpret 3.what is forward selection we select the best new factor and see if it's good enough (R^2, AIC, or p -value) add it to our model and fit the model with the current set of factors. Then at the end we remove factors that are lower than a certain threshold 4.what is backward elimination we start with all factors and find the worst on a supplied threshold (p = 0.15). If it is worse we remove it and start the process over. We do that until we have the number of factors that we want and then we move the factors lower than a second threshold (p = .05) and fit the model with all set of factors 5.what is stepwise regression it is a combination of forward selection and backward elimination. We can either start with all factors or no factors and at each step we remove or add a factor. As we go through the procedure after adding each new factor and at the end we eliminate right away factors that no longer appear. 6.what type of algorithms are stepwise selection? Greedy algorithms - at each step they take one thing that looks best 7.what is LASSO a variable selection method where the coefficients are determined by both minimizing the squared error and the sum of their absolute value not being over a certain threshold t 8.How do you choose t in LASSO use the lasso approach with different values of t and see which gives the best trade off 9.why do we have to scale the data for LASSO if we don't the measure of the data will artificially affect how big the coefficients need to be 10.What is elastic net? A variable selection method that works by minimizing the squared error and constraining the combination of absolute values of coefficients and their squares 11.what is a key difference between stepwise regresson and lasso regression If the data is not scaled, the coefficients can have artificially different orders of magnitude, which means they'll have unbalanced effects on the lasso constraint . 12.Why doesn't Ridge Regression perform variable selection? The coefficients values are squared so they go closer to zero or regularizes them 13.What are the pros and cons of Greedy Algorithms (Forward selection, stepwise elimination, stepwise regression) Good for initial analysis but often don't perform as well on other data because they fit more to random effects than you'd like and appear to have a better fit 14.What are the pros and cons of LASSO and elastic net They are slower but help make models that make better predictions 15.Which two methods does elastic net look like it combines and what are the downsides from it? Ridge Regression and LASSO. Advantages: variable selection from LASSO and Predictive benefits of LASSO . Disadvantages: Arbitrarily rules out some correlated variables like LASSO (don't know which one that is left out should be); Underestimates coefficients of very predictive variables like Ridge Regres sion 16.What are some downsides of surveys? Even if you what appears to be a representative sample in simple ways, maybe it isn't in more complex ways. 17.If we're testing to see whether red cars sell for higher prices than blue cars, we need to account for the type and age of the cars in our data set. This is called: Controlling 18.what is a blocking factor a source of variability that is not of primary interest to the experimenter 19.what is an example of a blocking factor The type of car, sports car or family car, is a blocking factor that it could account for some of the difference between red cars and blue cars. Because sports cars are more likely to be red; if we account for the difference, we can reduce the variability in our estimates 20.Under what conditions should you run A/B tests When you can collect data quickly. When the data is representative and the amount of data is small compared to the whole population 21.Do you have to decide the sample size ahead of time for A/B tests no, and we can run the hypothesis test anytime we want 22.What is full factorial design you test every combination and then use ANOV A to determine importance of each factor 23.What is fractional factorial design

The benefits of buying summaries with Stuvia:

Guaranteed quality through customer reviews

Guaranteed quality through customer reviews

Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.

Quick and easy check-out

Quick and easy check-out

You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.

Focus on what matters

Focus on what matters

Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!

Frequently asked questions

What do I get when I buy this document?

You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.

Satisfaction guarantee: how does it work?

Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.

Who am I buying these notes from?

Stuvia is a marketplace, so you are not buying this document from us, but from seller DrBellaPhD. Stuvia facilitates payment to the seller.

Will I be stuck with a subscription?

No, you only buy these notes for $12.49. You're not tied to anything after your purchase.

Can Stuvia be trusted?

4.6 stars on Google & Trustpilot (+1000 reviews)

53022 documents were sold in the last 30 days

Founded in 2010, the go-to place to buy study notes for 14 years now

Start selling
$12.49
  • (1)
Add to cart
Added