====== Class Activities ======
===== Ex. 1 =====
  * Install packages ISLR
  * use a dataset, Carseats
  * Build regression models with a DV, sales and IVs, your choices
  * Use ''?Carseats'' command for the explanation of the dataset
  * Use ''str'' function to see the characteristic of each variable. Make it sure that ''SelvesLoc'' variable should be factor, not int or anything.
  * 변인설명을 토대로 가설만들기 
    * 종속변인 = Sales
    * 독립변인 = 숫자변인 1 + 종류변인 1  (조별 선택)
    * Multiple regression without interactin
    * Multiple regression with interaction
  * 가설 만들기 
    * 종속변인 Sales
    * 독립변인 여러개 (interaction 없이)
    * Modeling 해 볼 것 

see [[:hierarchical regression]]
see also [[:statistical regression methods]] <- 많이 쓰이지 않음

  * <del>Make a full model (with all variables) then reduce down the model until you find it fitted.</del>
  * <del>Make a null model (with no variables) then, build up the model with additional IVs until you find a fitted model.</del> 
  * <del>Can we use ''step'' or ''stepAIC'' (MASS package needed) function?</del>
  * <del>Interpret the result</del>

<del>> step(lm.full, direction="back")</del>

[[./eg_script]] 

===== Ex. 2 =====
  * Install packages tidyverse
  * load the tidyverse
  * ''%%install.packages("car")%%''
  * ''%%install.packages("carData")%%''
  * load the car and the carData 
  * ''%%data("Salaries", package = "carData")%%''
  * ''%%?Salaries%%''
    * explain what it is
    * describe the data set
----
  * Regress sex variable on salary variable
  * Write the regression model 
  * Discuss the difference male and female (sex)

  * Use rank variable for the same purpose
  * Write the regression model 

  * Regress rank + sex on salary
  * How do you interpret the result?
  * And regress rank + sex + rank:sex on salary
  * How do you interpret this result?
  * Do factorial ANOVA test with rank and sex on salary 
  * How do you interpret the result?

  * Test regression model of your own choice
  * Interpret the result

-----
위의 Salaries 데이터사용이 안 될 때
  * download to R from here {{:salaries.csv}} 
    * use to import the data set. ''%%Salaries <- read.csv("http://commres.net/wiki/_media/salaries.csv")%%''
  * for information about Salaries (it may not be loaded), 
    * use ''%%??Salaries%%'' to describe the data set.
-----
Please copy and paste the proper r command and output to a txt file (use notepad or some other text editing program). You could use MS Word, but, please make it sure that you use type-setting fonts such as "Courier New." The below output, as an example, includes the r command ''%%head(Salaries)%%'' and the output. 
<code>

====== Discussion ======
Common topics
  * What affects students GPA? Or what determines students' GPA?

Group topics

====== Making Questionnaire ======
[[https://eclass2.ajou.ac.kr/webapps/discussionboard/do/forum?action=list_threads&course_id=_47711_1&nav=discussion_board_entry&conf_id=_52871_1&forum_id=_55560_1|Questions]] you submit at the ajoubb.
Then we will list questions in Google docs [[https://www.google.com/intl/ko_kr/forms/about/|Google survey]]