Descriptive Statistics Practical Statistics Descriptive Statistics
There are six statistics that will answer 90% of all questions!
There six are: Descriptive
There six are: Descriptive Chi-square
There six are: Descriptive Chi-square Z-tests
There six are: Descriptive Chi-square Z-tests t-tests
There six are: 5. Correlation (association)
There six are: 5. Correlation 6. Regression
Descriptive Statistics These are utilized to describe the characteristic of a population (parameter), or the characteristics of a sample (a statistic) Many business problems can be solved by knowing only descriptive statistics.
Geodemography http://www.youtube.com/watch?v=7UCxzYpXhpI
Geodemography
Geodemography
Descriptive Statistics Simple counts: frequency
Descriptive Statistics Simple counts: frequency The amount of time (in seconds) needed for assembly-line workers to complete a weld was recorded for 40 workers. 69 60 75 74 68 66 73 76 63 67 69 73 65 61 73 72 72 65 69 70 64 61 74 76 72 74 65 63 69 73 75 70 60 62 68 74 71 73 68 67 a. What is the frequency for each amount of time?
Descriptive Statistics Simple counts: histograms
Open the file called WeldDat.sav Do the following: Graphs Graphboard Template… Select WeldTime Select histogram with Normal… OK
Descriptive Statistics Simple counts: histograms
Descriptive Statistics Simple counts: ogive
Descriptive Statistics Simple counts: ogive http://mathworld.wolfram.com/Ogive.html
Symmetry
Right Left
Descriptive Statistics Back to the workers making welds….. The amount of time (in seconds) needed for assembly-line workers to complete a weld was recorded for 40 workers. 69 60 75 74 68 66 73 76 63 67 69 73 65 61 73 72 72 65 69 70 64 61 74 76 72 74 65 63 69 73 75 70 60 62 68 74 71 73 68 67 25
Descriptive Statistics Central tendency: A single number to represent a group.
Descriptive Statistics The average is 68.98. The standard deviation is 4.77. The amount of time (in seconds) needed for assembly-line workers to complete a weld was recorded for 40 workers. 69 60 75 74 68 66 73 76 63 67 69 73 65 61 73 72 72 65 69 70 64 61 74 76 72 74 65 63 69 73 75 70 60 62 68 74 71 73 68 67 27
Descriptive Statistics Central tendency: 1. Mode The most frequent score.
Descriptive Statistics Central tendency: 1. Mode 2. Median Half the numbers are larger, half are smaller.
Descriptive Statistics Central tendency: 1. Mode 2. Median 3. Mean The center of gravity of a distribution
Descriptive Statistics Central tendency: 1. Mode 2. Median 3. Mean Arithmetic Harmonic Geometric
Descriptive Statistics Central tendency: 1. Mode 2. Median 3. Mean Arithmetic
Descriptive Statistics Central tendency: 3. Mean Harmonic
Descriptive Statistics Central tendency: 3. Mean Harmonic
Descriptive Statistics Central tendency: 3. Mean Harmonic
Descriptive Statistics Central tendency: 1. Mode 2. Median 3. Mean Harmonic
Descriptive Statistics Central tendency: 1. Mode 2. Median 3. Mean Geometrical (For pure ratio numbers)
Does pricing following perception or volume? Geometric Mean: Does pricing following perception or volume? If a package holds twice as much should it be priced as twice that of a package that holds half as much?
Problem: Customers do not perceive volume correctly.
Geometric Mean: Does pricing following perception or volume? The perception of volume follows: Seven’s Law: How should this be done?
Descriptive Statistics Measure of Variation: Again a single number to represent a group.
Descriptive Statistics Measure of Variation: Range a. (Highest – Lowest) + 1 b. Subject to deviancy
Descriptive Statistics Measure of Variation: Range Mean Deviation a. Problem: Variation logically would be the average deviation around a measure of central tendency.
Descriptive Statistics Measure of Variation: Range Mean Deviation a. Problem: But… Always!!
Descriptive Statistics Measure of Variation: Range Mean Deviation a. Problem: So negative can be removed by looking at the absolute value.
Descriptive Statistics Measure of Variation: Range Mean Deviation a. Problem: Negative can be removed by squaring the value.
Descriptive Statistics Measure of Variation: Range Mean Deviation a. Problem: This is the definition of: 3. Variance
Descriptive Statistics Measure of Variation: Range Mean Deviation 3. Variance a. Problem: This is difficult to work with descriptively, so the square root can be taken.
Descriptive Statistics Measure of Variation: Range Mean Deviation 3. Variance a. This is called the: 4. Standard Deviation
The standard deviation is: Roughly the average difference scores are from the average. Or: It is roughly the average difference between two measures taken from the same population. It is an intuitive measure.
The amount of time (in seconds) needed for assembly-line workers to complete a weld was recorded for 40 workers. 69 60 75 74 68 66 73 76 63 67 69 73 65 61 73 72 72 65 69 70 64 61 74 76 72 74 65 63 69 73 75 70 60 62 68 74 71 73 68 67
Give the central tendency measures of this sample. What is the range, variance and standard deviation? Explain what you now know about the time it takes to make welds. d. When should a worker be reprimanded or fired for working too slow?
Give the central tendency measures of this sample.
Give the central tendency measures of this sample. What is the range, variance and standard deviation?
Give the central tendency measures of this sample. What is the range, variance and standard deviation? Explain what you now know about the time it takes to make welds.
Give the central tendency measures of this sample. What is the range, variance and standard deviation? Explain what you now know about the time it takes to make welds. When should a worker be reprimanded or fired for working too slow?