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Learning Objectives. 1.To show the difference between samples and populations2.To convert raw data into useful information3.To construct and use data arrays4. To construct and use frequency distributions5. To create histograms, polygons, and ogives6. To use frequency distributions to m
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1. Grouping and Displaying Data to Convey Meaning:Tables and Graphs
2. Learning Objectives 1. To show the difference between samples and populations
2. To convert raw data into useful information
3. To construct and use data arrays
4. To construct and use frequency distributions
5. To create histograms, polygons, and ogives
6. To use frequency distributions to make decisions
As a result of this class, you will be able to...As a result of this class, you will be able to...
3. Population vs. Sample
4. Population vs. Sample
5. Why Study Samples to Understand Population? 1) Easier than studying the whole population
2) Costs less
3) Takes less time
4) Sometimes testing involves risk
5) Sometimes testing requires the destruction of the item being studied
6. Why Study Samples to Understand Population? 1) Easier than studying the whole population
2) Costs less
3) Takes less time
4) Sometimes testing involves risk
5) Sometimes testing requires the destruction of the item being studied
7. Reliability of Data Ask the following questions:
1) What is the source of data?
2) Do the data support or contradict available evidence?
3) Is evidence missing that might cause us to come to a different conclusion?
4) What is the sample size? Does it represent the study group?
5) Is the conclusion logical and supported by data?
8. Numerical Data Presentation
9. Data Array 1. Organizes data to focus on major features
2. Data placed in rank order
smallest to largest (or largest to smallest)
3. Data in raw form (as collected)
24, 26, 24, 21, 27, 27, 30, 41, 32, 38
4. Data in ordered array
21, 24, 24, 26, 27, 27, 30, 32, 38, 41
10. Advantages/ Disadvantages ofData Array Advantages:
o Quickly notice lowest and highest values in the data
o Easily divide data into sections
o Easily see values that occur frequently
o Observe variability in the data
Disadvantage:
o Cumbersome
11. Presenting Data in Array: An Example
12. Presenting Data in Array: An Example
13. Numerical Data Presentation
14. Frequency Distribution What Is a frequency distribution?
Table that organizes data into mutually exclusive classes
Why called “frequency” distribution?
Shows number of observations from data set that fall into each class
What are the two classification schemes?
Discrete classes
Continuous classes
15. Constructing an Ungrouped Frequency Distribution
16. Constructing an Ungrouped Frequency Distribution
17. Constructing an Ungrouped Frequency Distribution
18. Constructing an Ungrouped Frequency Distribution
19. Constructing an Ungrouped Frequency Distribution
20. Steps in Constructing a Grouped Frequency Distribution 1. Determine the Class Interval Size
Ideally, we wish to generate a frequency distribution with 10 class intervals. If this is not possible when following the next series of steps, then we would rather have more, but never fewer (i.e. less) than 10 class intervals.
We would like the size (width) of each class interval to be in units of 1, 2, 3, 5, 10, 20, 30, 50, or multiples (factor of 10) of these values.
21. Steps in Constructing a Grouped Frequency Distribution 1. Determine the Class Interval Size (continued)
To Achieve These Goals, We Employ the Following Procedure:
22. 1. Determine the Class Interval Size (continued)
Example: Given the following data
100 74 84 95 95 110 99 87
100 108 85 103 99 83 91 91
84 110 113 105 100 98 100 108
100 98 100 107 79 86 123 107
87 105 88 85 99 101 93 99
R = 123 - 74 = 49
49/10 = 4.9
Tentative Class Interval Size = 5 Steps in Constructing a Grouped Frequency Distribution
23. 2. Determine the Starting Point (First Class Interval) of the Frequency Distribution
Start the Frequency Distribution with a Class Interval in Which the Following Guidelines Apply:
The First Number of the Class Interval is a Multiple of the Class Interval Size.
The First Interval Includes the Lowest Number or Value in the Data Set Steps in Constructing a Grouped Frequency Distribution
24. Steps in Constructing a Grouped Frequency Distribution
25. Additional Terms Associated with Grouped Frequency Distributions
26. Numerical Data Presentation
27. Histogram
28. Numerical Data Presentation
29. Frequency Polygon
30. Frequency Polygon
31. Frequency Polygon
32. Numerical Data Presentation
33. Ogive
34. Creating Grouped Frequency Distributions and Graphic Illustrations with MVPStats
35. Creating Grouped Frequency Distributions and Graphic Illustrations with MVPStats
36. Creating Grouped Frequency Distributions and Graphic Illustrations with MVPStats
37. Creating Grouped Frequency Distributions and Graphic Illustrations with MVPStats
38. Conclusion 1. Explained the difference between samples and populations
2. Converted raw data into useful information
3. Constructed and used data arrays and frequency distributions
4. Created histograms and polygons using MVPStats