{[ promptMessage ]}

Bookmark it

{[ promptMessage ]}

Chapter 3 notes - Chapter 3 Elementary Descriptive...

Info icon This preview shows pages 1–4. Sign up to view the full content.

View Full Document Right Arrow Icon
Chapter 3 – Elementary Descriptive Statistics Given precise enough measurement, even supposedly constant process conditions produce differing responses. For this reason we are not as interested in individual data values as we are in the pattern or distribution of the data as a whole. Section 3.1: Elementary Graphical & Tabular Treatment of Quant. Data Dot Diagram and Stem-and-Leaf Plots Example 3.1 : The government requires manufacturers to monitor the amount of radiation emitted through the closed door of a microwave. The following are radiation amounts emitted by 24 microwaves measured by one manufacturer. .01 .08 .05 .11 .02 .12 .08 .03 .10 .07 .10 .05 .10 .20 .01 .09 .05 .09 .02 .10 .18 .20 .30 .15 It is easiest to first order your data: .01 .03 .07 .09 .10 .18 .01 .05 .08 .10 .11 .20 .02 .05 .08 .10 .12 .20 .02 .05 .09 .10 .15 .30 Dot Diagram Stem-and-Leaf Plot – we use the first digit after the decimal place as the “stem” and the second as the “leaf” 1
Image of page 1

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

View Full Document Right Arrow Icon
-When there are too many observations appearing on one stem, we can split each stem into two. This can help produce a stem-and-leaf plot that gives a better indication of the distribution of the data. Other examples of splitting data into stem and leaf: Data Stem and Leaf for first observation 65, 70, 62, 56, … treat 6 as the stem and 5 as the leaf, etc. 2.6, 2.8, 3.1, 4.5, … treat 2 as the stem and 6 as the leaf, etc. 58.65, 62.87, 60.15, 59.72, … treat 58 as the stem and 65 as the leaf, etc. Back-to-back stem-and-leaf plots can be used to compare two data sets: Frequency tables and Histograms For frequency tables, we use intervals of equal length, but the number of intervals we use varies and is a matter of judgment. We also want to make sure that the endpoints of the intervals are set such that every data point is included in exactly one interval. Guidelines for making Histograms: Use intervals of equal length, show the entire vertical axis beginning at zero, avoid breaking either axis, keep a uniform scale across a given axis, and center bars of appropriate heights at the midpoints of the intervals. Example 3.1 continued: Frequency Table 2
Image of page 2
Histogram Some common distributional shapes that we can identify through the above graphical techniques: Bell-shaped or Normal Left-skewed (tail at left) Right–skewed (tail at right) Uniform Bimodal Truncated Scatterplots and Run Charts Example 3.2 : Scatterplot for ACT score and Highschool GPA for 12 students ACT 24 27 18 16 20 22 23 18 17 19 31 27 GPA 3.3 3.8 1.8 2.1 2.6 2.7 3.1 2.6 2.0 2.5 4.0 3.5 The scatterplot of GPA against ACT score shows a fairly strong positive linear relationship.
Image of page 3

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

View Full Document Right Arrow Icon
Image of page 4
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}

What students are saying

  • Left Quote Icon

    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.

    Student Picture

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

  • Left Quote Icon

    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.

    Student Picture

    Dana University of Pennsylvania ‘17, Course Hero Intern

  • Left Quote Icon

    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.

    Student Picture

    Jill Tulane University ‘16, Course Hero Intern