By Thom Marra
Marra & Associates, LLC
The Big Picture
 Know your story line, the Y’s and the X’s
 Think through what statistics you are likely to use
 Collect the data
 How much data do you have?
 Is it stable?
 See the data (graphs and tables)
 Analyze using descriptive and inferential statistics
Marra & Associates, LLC
Know the Story Line
 Determine what is your primary metric(s)
 The Y in Y = f(x)
 What is the business reason for collecting the data?
 Do an initial thought process on relationships to Y
(what are the X’s in Y = f(x))
Marra & Associates, LLC
Data Collection – types of data
 Continuous
 Discrete
 Binary
 Ordinal
 Nominal
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Data Visualization
 Look for outliers
 Fix spelling and grouping errors
 Graphs for continuous data
 Graphs / tables for discrete data
 Annotating graphs
Marra & Associates, LLC
Data Visualization - outliers
 Time series plot
 Open Newmarket.mtw
 Graph/time series plot
Marra & Associates, LLC
Data Visualization - spelling
 Spelling errors cause improper subgroups
 Open Exh_tabl.mtw
 Stat/tables/tally individual values
Marra & Associates, LLC
Data Visualization – continuous data
 A list from the graph’s menu
Use stat/regression/fitted line plot
Use stat/basic stats/graphical
summary
Marra & Associates, LLC
Data Visualization – scatterplot
 Use scatterplots when Y and X are continuous
 Use stat/regression/fitted line plot
 Open Exh-regr.mtw
Marra & Associates, LLC
Data Visualization - histograms
 Use histograms to visually see the shape of the data
 Use stat/basic statistics/graphical summary
 Open Pulse.mtw
Marra & Associates, LLC
Data Visualization – boxplots
 Use boxplots when you have more than 30 data points
per subgroup
 Open Pulse.mtw
 Graph/boxplots
Marra & Associates, LLC
Data Visualization – individual value plot
 Use individual value plots when you have small
amount of data for each subgroup
 Open Pulse.mtw
 Graph/individual value plot
Marra & Associates, LLC
Data Visualization – individual value plot
Marra & Associates, LLC
Data Visualization - tables
 Tables are the best way to display exact numerical
values for small data sets
This table is easier to
compare values than the Pie
chart.
Group Before After
A
53
60
B
46
40
C
57
55
Marra & Associates, LLC
Marra & Associates, LLC
Data Visualization – Pareto Charts
 Open Exh_qc.mtw
 Stat/Quality Tools/Pareto
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Data Visualization - annotation
 Make sure all worksheet are named properly
 Tools/Options/Graphics/Annotation/My Footnotes
Marra & Associates, LLC
Data Visualization - annotation
 Make sure all column names are clear, spelled correctly
and carry the proper capitalization.
 From the Tool bar select “T” and add text to clarify
graphs.
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Marra & Associates, LLC
Data Analysis – population attributes
 Location 
S p r e a d
SHAPE
Cy
CONSISTeN
Marra & Associates, LLC
Data Analysis – descriptive statistics
 Open Furnace.mtw
 Stat/Basic Statistics/Graphical Summary
Marra & Associates, LLC
Data Analysis – conclusions
 Follow the roadmap for additional hypothesis tests
 Use GLM or Multiple Regression for more than one X
 Make a list of the “Vital Few X’s.” Also make a list of those




X’s that were the “Trivial Many.”
Draw conclusions based on all of your knowledge
(scientific principles, wisdom of the wise, graphical and
statistical output)
Make practical decision. Remember you cannot have a
practical difference if there is not a statistical difference.
Solve the current opportunity and move on to the next
opportunity
Have fun!
Marra & Associates, LLC
Marra & Associates, LLC