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Transcript
1


Did your
project
reduce
variation or
shift the
mean?
How do you
demonstrate
improvements
statistically?
2
VIII-47



The question one needs to ask
during a project is whether the
changes made as the result of a
Black Belt project have made a
difference in the process.
The question is, “Has the project
made a difference, and if so, how
confident are we that the
difference is statistically
significant?”
We strive for 95% confidence or
better (α=.05).
3
VIII-47

A hypothesis is:

Examples:
◦ a tentative explanation for an
observation that can be tested by further
investigation.
◦ taken to be true for the purpose of
investigation; an assumption.
◦ Average gas mileage differs depending
on type A or B gas.
◦ Probability of death in auto accidents
differs depending on seat belt usage.
◦ The type of aspirin determines the
amount of pain relief.
◦ A Six Sigma Black Belt project produced
significant results with regard to mean
and/or standard deviation improvement.
4
VIII-47

We set up 2 hypotheses
◦ H0 is called the null hypothesis
 what is being tested
 must contain an =
 assumed to be true
◦ H1 is called the alternate hypothesis

Based on the data we collect, we
must decide in favor of either H0
or H1. Which does the evidence
support?
◦ You can only reject null, or fail to
reject null
5
VIII-47
Define the problem and state objectives
State a “Null Hypothesis” (Ho)
State the “Alternative Hypothesis” (H1)
Establish significance level (a) and
determine the critical value
Collect sample data
Calculate test statistic and/or p-value
DECIDE:
What does the evidence suggest?
Reject Ho? or Fail to reject Ho?
6
VIII-47


Set up the statapult and reduce
obvious variation
Pick a factor that you would like
to test
◦ Ball type
◦ Operator
◦ Etc



Pick at least 3 different
treatments (levels)
Record data with at least 5 data
points each population
Analyze
7
VIII-83


Set up the statapult and reduce
obvious variation
Pick two factors that you would
like to test
◦
◦
◦
◦



Ball type
Operator
Pull back angle
Etc.
Pick at least 2 different levels for
each factor
Record at least 5 data points
each
Analyze
8
VIII-87