Tutorial Exercises Week 4

Read in the dataset: tutorial-data-cleaning.csv. After reading in the “raw” data, the first six rows of the data should look like this:

  Sales_Data     Date     Sales Promotion.Sales
1         NA 03.16.18      9657              NA
2         NA 02.08.18      8886              NA
3         NA 04.13.18 Promotion           42312
4         NA 04.14.18 Promotion           35969
5         NA 02.04.18      6500              NA
6         NA 03.24.18      4854              NA

The goal of this exercise is to clean this dataset and provide some summary statistics about the cleaned data. When the data is cleaned, the first six rows should look like this:

          date sales promotion
1   2018-02-01 22455      TRUE
2   2018-02-02 43011      TRUE
3   2018-02-03  6471     FALSE
4   2018-02-04  6500     FALSE
5   2018-02-05 26509      TRUE
6   2018-02-06  2247     FALSE

Complete the following steps to clean the data to get it to look like the 2nd data extract:

• Drop the variable Sales_Data.
• Correctly format the “Date” variable as a date.
• Sort the dataset by date. Create a logical variable called promotion which is TRUE whenever there was a promotion (indicated by a non-NA value in the Promotion.Sales variable or the word Promotion in the Sales variable) and FALSE otherwise.
• Whenever the word "Promotion" appears in the Sales variable, replace it with the corresponding value in Promotion Sales.
• Drop the Promotion.Sales variable.
• Convert the Sales variable from character to numeric.
• Dropping any remaining rows with missing values.
• Convert all variable names to lower case.

Use the techniques discussed in Chapter 13 of the online book to create these data, and use the resulting data to answer the following questions.

Question 1

How many rows are in the final cleaned dataset?

Question 2

On how many days were there promotions?

Question 3

What is the average of the cleaned sales variable?

Question 4

What is the average daily sales on days where there were promotions?

Question 5

On which date in April is the median date of the cleaned dataset?