====== Getting and Cleaning Data ======

Course page: https://class.coursera.org/getdata-034
By Jeff Leek, PhD, Roger D. Peng, PhD, Brian Caffo, PhD

  * Basic concepts:
    * Find and extract raw data
    * Tidy data principles 
    * practical R packages

  * Interesting datasets from: https://data.baltimorecity.gov/
  * Pipeline: **Raw data -> Processing script -> tidy data** -> data analysis -> data communication

  * **Components of tidy data**
    * Raw data: can have multiple levels
    * Tidy data
    * Should produce a code book (metadata):
      * could be in markdown
      * should have a section called "Study design" (eg. how raw data was collected)
      * must have section "Code cook": description of each variable and its units
    * Explicit and exact recipe to go from raw to tidy (instruction list)
      * R script
      * input = raw data, output = processed data
      * no parameter for script