STK2100 - Vår 2019

Lekser / Exercises

Week 1:
- no exercises
Week 2:
- exercises 2.1 - 2.5, 2.7, 2.11 of the text book. (solutions R)
Week 3:
- exercise 1, points (a), (b), (c) and (d) of the last year 1st mandatory assignment (here the original in Norwegian by Geir Storvik - note that only page 2 is relevant, until "Hvilken fortolkning har γ-ene i dette tilfellet.");
- exercise 4.10, points (a), (b), (c) and (d) in ISL book. Note:
  - with "confusion matrix" the book means the table we saw in lecture 5 (page 3 of the notes).
  - code to get the data.
  - solutions R
Week 4:
- Exercises 3.1 - 3.4 of the text book.
- Solutions
Week 5:
- Exercises 5.2 and 5.8 in ITSL book;
- Download the body fat data (here the R code to do that). It contains a response variable (pcfat, percentage of body fat) and 13 explanatory variables (age and 12 measures of different body part circumferences). Fit a linear Gaussian model by using both backward elimination and forward selection, in both cases using AIC as stopping criterion. Do you obtain the same model with both procedures? Comment the result.
- Solutions
Week 6:
- For Gaussian linear regression, show that the variance of the ridge estimator is smaller than the variance of the ordinary least square estimator;
- Exercises 6.3, 6.4, 6.10 and 6.11 in ISL book (note that the dataset for the last exercises is in the R-package MASS).
- Solutions, code.
Week 7:
- Exercises 4.3 and 4.5 of the text book;
- Exercises 7.2, 7.3, 7.5, 7.6, 7.9, 7.11 and 7.12 in ISL book, pages 298-301 (note that the dataset for exercise 7.6 is in the R-package ISLR, that for exercise 7.9 in the R-package MASS).
- Solutions, code.
Week 8:
- Exercises 5.3, 5.4 and 5.5 of the text book;
- Exercises 4.1, 4.9 and 4.10 (a, b, c and d) in ISL book, pages 168-171
- Solutions
Week 9:
- Exercise 5.8 of the text book;
- Exercise 4.2 in ESL book, page 135 (points (a) and (e) are related to exercises 5.9 and 5.10 of the text book, respectively).
- Solutions
Week 10:
- Exercises 4.8 and 5.11 of the text book;
- Exercises 8.3 and 8.8 (points (a), (b) and (c)) in ISL book, pages 332 and 333)
- Solutions and code
Week 13:
- Extra exercises 6, 7, and 11 from this file (by Geir O. Storvik)
- Solutions, code
Week 14:
- Exercises 10.1 (page 413), 10.3 (page 414) and 10.10 (page 417) in ISL book
- Solutions, code
Week 15:
- Exercises 10.4 (page 414) and 10.9 (page 416) in ISL book
- Code

Publisert 14. jan. 2019 10:57 - Sist endret 16. nov. 2023 11:45