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Unformatted text preview: Lecture 5: Descriptive Measures Lecture 5: Outline 1. Questions about PS1 – Due date: Jan25 until Jan27, 50% max. Jan28 until Feb01 (before class) – Review of first drafts on Feb01; You can submit revised PS1 by Feb03 – StemandLeaf Plot – Frequency Distribution, Histogram – 2 categorical variables 1. New Material: Descriptive Measures – Describe a numerical variable with 3 concepts of Central Tendency, Variability, and Shape : 1. Central Tendency (Mean, Median, Mode) 2. Variability (Range, Interquartile Range, Standard Deviation, Coefficient of Variation) Next lab class Tuesday, Feb01 Chapter3 ‘AUTOS_Fall2010 PS1.xls’ Contingency Table: Presents the result of 2 categorical variables as cross tabulations Frequency Table Tally the 120 responses according to their SUV/nonSUV and Drive Type e.g., In this sample, 3 nonSUVs with AWD Percent Table (based on % of Row Total) Tally responses based on their percentage of SUV or nonSUV type e.g., In this sample, 3.37% of all nonSUVs have AWD We could also create Percent Tables: Based on Percent of Overall Total (e.g., In this sample, x% of all cars have AWD) Based on Percent of Column Total (e.g., In this sample, x% of cars with AWD are nonSUVs) What we have done so far to summarize and describe numerical variables: Possible values Count of observations / values in the sample StemandLeaf Plot Frequency Distribution and Histogram Possible values of some variable (a phenomenon where observations vary from trial to trial) – here: SQFT Count of observations / values in the sample Data, Single Variable Control Charts Describe Numerical Categorical Time Series Plot Not Time Series or Stable Time Series 1. Frequency Table 2. Percent Table Summary Measures Central Tendency 1. Mean 2. Median 3. Mode Shape 1. 5 Number Summary 2. Skewness 3. Kurtosis 4. Outlier 5. Normal (bell shape) 6. Normal Probability Plot Variability___ 1. Range 2. IQR 3. Standard Deviation 4. Coefficient of Variation SummaryT ables 1. Stem & Leaf Display 2. Frequency, Percent, Cumulative Percent Charts, Graphs, Plots 1. Frequency Histogram 2. Percentage Histogram 3. Frequency Polygon 4. Percentage Polygon 5. Cumulative % Polygon 6. Boxplot Numerical Collected over time Categorical Collected over time PChart 1. Data collected on whether an item is nonconforming or not (2 categories). 2. Sample of items is collected each time period for a number of time periods. A sample of numerical data each time period Mean and Range Chart 1. Bar Chart 2. Pie Chart 3. Pareto Chart Summary Tables Charts Look for trends or patterns over time CHAPTER 3: DESCRIPTIVE MEASURES CHAPTER 3: Descriptive Measures With the tables and charts, we get a picture of what the distribution looks like....
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 Spring '08
 Reardon,J
 Standard Deviation, Interquartile range, Quartile

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