Chapter 2 presenting data in charts and tables
This presentation is the property of its rightful owner.
Sponsored Links
1 / 30

Chapter 2 Presenting Data in Charts and Tables PowerPoint PPT Presentation


  • 99 Views
  • Uploaded on
  • Presentation posted in: General

Chapter 2 Presenting Data in Charts and Tables. Why use charts and graphs? Visually present information that can’t easily be read from a data table. Many details can be shown in a small area.

Download Presentation

Chapter 2 Presenting Data in Charts and Tables

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Chapter 2 presenting data in charts and tables

Chapter 2Presenting Data in Charts and Tables

Why use charts and graphs?

  • Visually present information that can’t easily be read from a data table.

  • Many details can be shown in a small area.

  • Readers can see immediately major similarities and differences without having to compare and interpret figures.


Chapter 2 presenting data in charts and tables

Computer software can be used to create charts and graphs:

  • SPSS

  • MINITAB

  • Ms. Excel

  • Ms. Visio

  • Others


Chapter 2 presenting data in charts and tables

How to present categorical data?


Chapter 2 presenting data in charts and tables

Bar chart

  • Bar chart and pie chart are often used for quantitative data(categorical data)

  • Height of bar chart shows the frequency for each category

  • Bar graphs compare the values of different items in specific categories or t discrete point in time.


Chapter 2 presenting data in charts and tables

Bar chart example:


Chapter 2 presenting data in charts and tables

Pie chart

  • The size of pie slice shows the percentage for each category

  • It is suitable for illustrating percentage distributions of qualitative data

  • It displays the contribution of each value to a total

  • It should not contain too many sectors-maximum 5 or 6


Chapter 2 presenting data in charts and tables

Pie char example:


Chapter 2 presenting data in charts and tables

Table example:


Chapter 2 presenting data in charts and tables

How to present numerical data?


Chapter 2 presenting data in charts and tables

The ordered array

The sequence of data in rank order:

  • Shows range (min to max)

  • Provides some signals about variability within the range

  • Outliers can be identified

  • It is useful for small data set

    Example:

  • Data in raw form: 23 12 32 567 45 34 32 12

  • Data in ordered array:12 12 23 32 32 34 45 567

    (min to max)


Chapter 2 presenting data in charts and tables

Tabulating Numerical Data:

Frequency Distribution

  • A frequency distribution is a list or a table….

  • It contains class groups and

  • The corresponding frequencies with which data fall within each group or category

    Why use a Frequency Distribution?

  • To summarize numerical data

  • To condense the raw data into a more useful form

  • To visualize interpretation of data quickly


Chapter 2 presenting data in charts and tables

Organizing data set into a table of frequency distribution:

  • Determine the number of classes

    The number of classes can be determined by using the formula: 2k>n

    -k is the number of classes

    -n is the number of data points

    Example:

    Prices of laptops sold last month at PSC:

    299, 336, 450, 480, 520, 570, 650, 680, 720

    765, 800, 850, 900, 920, 990, 1050, 1300, 1500


Chapter 2 presenting data in charts and tables

In this example, the number of data points is n=18.

If we try k=4 which means we would use 4 classes, then 24=16 that is less than 18. So the recommended number of classes is 5.

  • Determine the class interval or width

    -The class interval should be the same for all classes

    -Class boundaries never overlap


Chapter 2 presenting data in charts and tables

-The class interval can be expressed in a formula:

Where i is the class interval, H is the highest value in the data set, L is the lowest value in the data set, and k is the number of classes.

In the example above, H is 1500 and L is 299. So the class

interval can be at least =240.2. The class

interval used in this data set is 250

  • Determine class boundaries: 260 510 760 1010 1260 1510

  • Tally the laptop selling prices into the classes:

    Classes:

    260 up to 510

    510 up to 760

    760 up to 1010

    1010 up to 1260

    1260 up to 1510


Chapter 2 presenting data in charts and tables

  • Compute class midpoints: 385 635 885 1135 1385

    (midpoint=(Lower bound+ Upper bound)/2)

  • Count the number of items in each class. The number of items observed in each class is called the class frequency:

    Laptop selling Frequency Cumulative Freq.

    price9($)

    260 up to 510 44

    510 up to 76059

    760 up to 1010615

    1010 up to 1260116

    1260 up to 1510218


Chapter 2 presenting data in charts and tables

Step-and-leaf

  • A statistical technique to present a set of data.

  • Each numerical value is divided in two parts—stem(leading digits), and leaf(trailing digit)

  • The steps are located along the y-axis, and the leaf along the x-axis.


Chapter 2 presenting data in charts and tables

Stem Leaf

299

336

450

480

520

570

650

680

720

760

800

850

900

920

990

1050

1300

1500


Chapter 2 presenting data in charts and tables

Histogram

  • A graph of the data in a frequency distribution

  • It uses adjoining columns to represent the number of observations(frequency) for each class interval in the distribution

  • The area of each column is proportional to the number of observations in that interval


Chapter 2 presenting data in charts and tables

Example of histogram:


Chapter 2 presenting data in charts and tables

How can you construct the histogram in SPSS?


Chapter 2 presenting data in charts and tables

Polygon

  • A frequency polygon, like a histogram, is the graph of a frequency distribution

  • In a frequency polygon, we mark the number observations within an interval with a single point placed at the midpoint of the interval, and then connect each set of points with a straight line.


Chapter 2 presenting data in charts and tables

Polygon example:


Chapter 2 presenting data in charts and tables

How can you construct the polygon in SPSS?


Chapter 2 presenting data in charts and tables

Ogive—a graph of cumulative frequency

Ogive example:


Chapter 2 presenting data in charts and tables

How can you construct the Ogive in SPSS?


Chapter 2 presenting data in charts and tables

Exercises

  • The price-earnings ratios for 24 stocks in the retail store are:

    8.29.79.48.711.312.8

    9.211.810.810.39.512.6

    8.88.610.612.811.69.1

    10.412.111.59.911.112.5

  • Organize this data set into step-and-leaf display

  • How many values are less than 10.0?

  • What are the smallest and largest values


Chapter 2 presenting data in charts and tables

Exercises

2. The following stem-and-leaf chart shows the number of units produced per day in a factory.

  • 81

    41

  • 62

  • 013335599

  • 023677816

  • 5918

  • 0015623

    103625


Chapter 2 presenting data in charts and tables

  • How many days were studied?

  • How many values are in the first class?

  • What are the smallest and the largest values?

  • How many values are less than 70?

  • How many values are between 50 and 70?


Chapter 2 presenting data in charts and tables

3. The following frequency distribution represents the number of days during a year that employees at GDNT were absent from work due to illness.

Number of Number of

Days absentEmployees

0 up to 45

4 up to 810

8 up to 126

12 up to 168

16 up to 202


Chapter 2 presenting data in charts and tables

  • What is the midpoint of the first class?

  • Construct a histogram

  • Construct a frequency polygon

  • Interpret the rate of employee absenteeism using the two charts


  • Login