Formative Test 1

Instructions

Please follow the directions below and submit your answers by 5pm EST, Thursday 5th of October

1. Download the MITx/Harvardx MOOC dataset.

2. Fork and clone this repository to your computer and open it as a new project in RStudio

3. Open a new R Markdown file and save it to the repository with the filename formative.rmd. Inlcude all your code in the markdown document.

4. Upload the MITx/Harvardx dataset to R as a dataframe named D1(Please inlcude your code in your markdown document)

5. What does the DI suffix that is appeneded to two of the variable names mean?

6. How many people enrolled in HarvardX/CS50x recieved certification in 2012? (Please inlcude your code in your markdown document)

7. How many people registered for HarvardX/CS50x from Colombia on October 15, 2012? (Please inlcude your code in your markdown document)

8. Create a new data frame (D2) that includes student ID and registration date for all students from a country of your choice (Please inlcude your code in your markdown document)

9. Create a new data frame (D3) in which the column names are the registration dates, with one column containing the student ids and all other cells indicating a 1 if the student registered on that date or an NA if they did not (hint: you will need to create a new variable before you change the structure of your data frame)

10. Now make the row names of D3 the student ids on your new data frame and remove the user id column from your data frame

11. Convert your data frame to a matrix (M1)

12. Create a new matrix which is the transposed version of your matrix (M2)

13. Create a third matrix (M3) that is a student by student matrix where the cells in the matrix represent if two studentes registered on the same day (This will take a lot of processing power, you may not be able to complete it if you have a large number of students)

14. Convert the diagonal of your matrix into NAs