1
$\begingroup$

I am currently reading the book "Introduction to statistical learning" and on Page 3 there is a problem statement regarding the SMarket data (stock exchange data) fig 2.2 whose left panel states the relation shown is the percentage vs up/down trend of stock market. But here Author is saying that one box for 648 days and one for 602 days.

I don't quite get that. There is no information given for the days. Is the print faulty or am I missing something here? If someone has gone through the book and has any idea, please help me to understand the following chart.

picture of the book page in question

$\endgroup$
  • 1
    $\begingroup$ perhaps he means the number of data points represented in each box plot? $\endgroup$ – tintinthong Aug 28 '17 at 5:15
4
$\begingroup$

The left-handed panel of Figure 1.2 displays two boxplots of the previous day's percentage changes in the stock index: one for the 648 days for with the market increased on subsequent days, and one for the 602 days for which the market decreased.

The blue boxplot of the left-most figure is based on data from 648 days. These days are not randomly chosen, they are selected because they have a special characteristic: the day after the market increased. The red boxblot in the left-most figure is based on 602 days for which the market decreased the day after.

In short, the red and blue boxplot visualize multiple datapoints.

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.