QMM240_W08_DataVisualization

QMM240_W08_DataVisualization - QMM 240 Graphical Data...

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QMM 240 Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 1 Data Visualization Data visualization and analysis: Explore Gain insight Summarize, describe Communicate findings Characteristics of univariate data Measurement Units? Discrete or continuous? Missing data? Accuracy? Sampling or data collection method? Central tendency or Location Data concentration? Typical or "middle values? Dispersion How variable? Unusual values? Shape Symmetric? Skewed? Flat? Peaked? Multimodal? Example: PERatios.xls
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QMM 240 Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 2 Measurement Units? Current stock price / earnings per share in last 12 months Accuracy? Discrete? Sampling? Missing data? Sorting Good first step with small datasets Finds missing data Outliers or unusual values Mechanics of Excel sorting Sort keys, asc and dsc to find missing Don't garble your dataset
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QMM 240 Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 3 A first look at Histograms A graphical representation of sorted data Let's create using Excel and Megastat Histogram 0 5 10 15 20 25 30 5 15 25 35 45 55 65 P/E Ratio Percent Central tendency ? Variation? Skewness? Unusual observations? Dot Plots Simple graphical display of n individual values of numerical data Easy to understand Not good for large samples (e.g., > 5,000)
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QMM 240 Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 4 Let's create using MegaStat and then see how it's actually just an Excel X-Y scatter plot.
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QMM 240 Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 5 Frequency Distributions and Histograms Classify n data points in to k classes (a.k.a. bins) 1) Sort data 2) Number of bins n # bins n # bins 16 5 2048 12 32 6 4096 13 64 7 8192 14 128 8 16384 15 256 9 32768 16 512 10 65536 17 1024 11 131072 18 3) Bin limits 4) Compute frequencies and put in table Counts or frequencies Graph to form histogram Example: Rents.xls
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Graphical Data Visualization Statistical Methods for Business I - Lecture Notes Page: 6 Can plot cumulative using Ogive option If you sort the frequencies in descending order and graph with a bar chart, we get a Pareto chart. Commonly used in prioritization of competing problems
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This note was uploaded on 04/01/2008 for the course QMM 240 taught by Professor Isken during the Winter '08 term at Oakland University.

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QMM240_W08_DataVisualization - QMM 240 Graphical Data...

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