Stats Tools for Analyzing Data Chapter 18

Objectives Review of hypothesis Testing Overview of FMEA Overview of Design of Experiment Class Exercise

Hypothesis testing Definition Procedure that summarizes data so you can detect differences among groups

Data Types Discrete Continuous

Hypothesis outcomes Truth Conclusion or Decision Groups Same Groups Different Accept Ho: groups are same No Error Type II Error Reject Ho: groups are different Type I Error

Procedure Null vs. Alternative Hypothesis When comparing groups from different processes we assume: Each process is stable No time related changes are involved Data is unbiased

Stat testing Data Type Test Purpose Continuous T – test Compare Average ANOVA Compare 2 or more group averages F- test Compare 2 or more variances Discrete Chi-square Compare 2 or more proportions

F test Is the ratio of 2 variances Is skewed with a tail to the right. The lower bound is 0 The mode is almost 1 Depends on 2 separate d.f. Assumes each group of data is a Normal distribution

FMEA (Failure Modes & Effects Analysis) Purpose A structured approach to identify, estimate, prioritize, and evaluate risk Conducting FMEA Brainstorm potential failure Identify impact Identify courses Determine rate of ability to detect future failure Calculate RPN Focus on high RPN and reduce or eliminate those risks

Design of Experiment (DOE) Identify “vital few” Root cause analysis DOE procedure Class exercise

Any questions?