stat-60_lect-03_April_03

# stat-60_lect-03_April_03 - 3 Example 4 x min 1stQ median...

This preview shows pages 1–5. Sign up to view the full content.

STATS 60, Spring 2008 April 3, Lecture 03 1 More on box plots (and histograms) Example 1 Consider the sample x = - 2 , - 2 , - 1 , - 1 , 0 , 0 , 0 , 0 , 1 , 1 , 1 , 1 , 2 , which has 13 elements. To create a histogram, stack the observations along the number line. To find quantiles, unstack the observations and put them in serial order. The 25th percentile (1st quartile) is at element number 0 . 25( n + 1) , the 30th percentile is at element number 0 . 30( n + 1) and so on. 1

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Example 2 x min 1stQ median 3rdQ max mean 1 -3, -2.5, -2, -1.5, -1, -0.5, 0, 0.5, 1, 1.5, 2, 2.5, 3 -3 -1.5 0 1.5 3 -0.00 Notes: x is a sequence mean = median The scale for the density curve is not shown in the histogram. The density curve is a smoothed version of the histogram adjusted so that its total area equals 1.0. 2
Example 3 x min 1stQ median 3rdQ max mean 2 -3, -2.5, -2, -1.5, -1, -0.5, 0, 0.5, 1, 1.5, 2, 2.5, 8 -3 -1.5 0 1.5 8 .38 Notes: x is a sequence with last observation changed mean > median SD increased sample distribution is right tailed one outlier upper whisker is the maximum with outliers skipped

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: 3 Example 4 x min 1stQ median 3rdQ max mean 3-2.29, -1.66, 0.51, 0.79, 0.98, 0.99, 1.11, 1.14-2.29-0.03 0.89 1.02 1.14 0.20 Notes: • sample distribution is left-tailed • mean < median • When R draws histograms, it uses the ﬁve number summary, where the upper/lower hinges are obtained as the median of the observations above/below the median. This is more complicated than simply using the 1st and 3rd quartile. Using the quartiles is ﬁne for this class. The 1st and 3rd quartiles are given in the box plot in parentheses. • The tail that’s heavy will either have a longer whisker or an outlier(s). 4 Example 5 x min 1stQ median 3rdQ max mean 1-0.37, 0.09, 0.21, 0.26, 0.59, 0.59, 0.74, 1.69-0.37 0.18 0.43 0.63 1.69 0.47 Notes: • sample distribution is right-tailed • mean > median • one outlier • upper whisker is the maximum with outliers skipped 5...
View Full Document

{[ snackBarMessage ]}

### What students are saying

• As a current student on this bumpy collegiate pathway, I stumbled upon Course Hero, where I can find study resources for nearly all my courses, get online help from tutors 24/7, and even share my old projects, papers, and lecture notes with other students.

Kiran Temple University Fox School of Business ‘17, Course Hero Intern

• I cannot even describe how much Course Hero helped me this summer. It’s truly become something I can always rely on and help me. In the end, I was not only able to survive summer classes, but I was able to thrive thanks to Course Hero.

Dana University of Pennsylvania ‘17, Course Hero Intern

• The ability to access any university’s resources through Course Hero proved invaluable in my case. I was behind on Tulane coursework and actually used UCLA’s materials to help me move forward and get everything together on time.

Jill Tulane University ‘16, Course Hero Intern