Hi everyone! Read through the material below, watch the videos, work on the Excel lecture and follow up with your instructor if you have questions.

 

Learning Outcomes.

  • Collect, organize and graph raw data.
  • Know the difference between numerical and categorical variables.
  • Create grouped frequency distributions and histograms. Class intervals should be of equal width, chosen to effectively reveal informative patterns in the data, between 5 (for overview) and 15 (for some detail).
  • Describe a graphical display by first describing the overall pattern (e.g., roughly symmetrical or skewed right or left) and then deviations from that pattern, such as outliers.
  • Understand that the vertical axis of the histogram may be scaled for frequency or percentage (proportion), but the choice of vertical scaling will not affect the important features revealed by a histogram.
  • Excel: know how to freeze panes, sort and filter data, format tables, make charts and use pivot tables.

Topic. This lesson covers: Graphical Descriptive Techniques

WeBWorK: Sets 1.3, 2.1 & 2.2 – due 9/10 at noon

OpenLab Assignment 2- due 9/7 at midnight

Excel Lecture 2Download

Creating a Histogram – Example from Excel Lecture 2 

Powerpoint slides for Lecture 2Download

Below you will find videos to help you organize and display data in Excel. By 2016, Microsoft had added a histogram to its charts. By clicking on the bottom axis, you can specify the number of bins or the class width. A further option is to use the data array calculation “frequency”. Here is a step-by-step guide. Once you have the table, you can create appropriate labels using columns of the left and right boundaries for each interval and  the “concatenate” function.

Videos

Displaying and comparing data

Quantitative Data in Excel
Creating a Cumulative Frequency Distribution in Excel
Stem and Leaf Plot in Excel

While Excel does not have something builtin for stem and leaf plots, there are macros available.

The applied view

Watch the video Stemplots.

  1. List some of the variables that were taken on soldiers for the sizing data bank.
  2. What was the overall shape of the distribution of soldiers’ foot lengths?
  3. About where was the center of the distribution?
  4. What variable was used to measure fuel economy on Toyota’s line of vehicles?
  5. Focus on the stemplot of fuel economy for Toyota’s 2012 line. What new information became evident (or more clear) when the stem was expanded?
  6. What was learned from back-to-back stemplots about the change in fuel economy in Toyota’s vehicle line from 1984 to 2012?

Watch the video Histograms.

  1. The video opens by describing a study of lightning strikes in Colorado. What variable does the first histogram display?
  2. In this lightning histogram, what does the horizontal scale represent? What does the vertical scale represent?
  3. Was the overall shape of this histogram symmetric, skewed, or neither?
  4. Why were a few values in the second lightning histogram called outliers?
  5. When you choose the classes for a histogram, what property must the classes have if the histogram is to be correct?
  6. What happens to a histogram if you use too many classes? What happens if you use too few?