Stat Uses Flashcards
Mean (xBar)
Value that is the sum of the values divided by the number of values in a data set
Median
Value positioned in the middle of a data set
Mode
Value that appears most often in a data set
Range
Subtract the smallest value from the largest value in a data set
Mean Absolute Deviation (MAD)
Distance of a value from the Mean in Absolute Value
Variance
MAD divided by number of values in a data set
Standard Deviation (SD)
The square root of Variance
External Environment Factors
Technology, Social & Cultural Elements, Economics, Legal & Political Elements, Competition
Internal Environment Factors
Attribute measures, Effectiveness measures, Efficiency measures
VOC
Identify customer, capture voice of customer, collect and analyze, formulate conclusions, act on conclusions
Quality Function Deployment (QFD)
Convert customer expectations into technical requirements for each stage of product or service development and production
House of Quality (QFD)
WHAT identifies customer requirements
HOW identifies technical requirements
Competitive Evaluation measures how well all products available meet customer expectations
Average Rate of Return (ARR)
net annual savings / average investment
Payback Period
initial investment / net annual cash savings
Discounted Cash Flow (DCF)
Use DCF table to find % of discount over period of time
Net Present Value (NPV)
Use DCF tables to find % of discount over years to initial investment
Internal Rate of Return (IRR)
Use DCF to determine the interest rate that will make the DCF equal to the initial investment
Unit
What you make
Defect
Output that does not meet external or internal customer expectations
Opportunity
The chance to satisfy the customer or generate a defect
DPU
Defects per unit
DPMO
Defects per million opportunities
Number of defects / (number of opp x number of units) x 1,000,000
Six Sigma
3.4 defects per million oppotunities
Yield
1 - % defects
Rolled Throughput Yield (RTY)
Determines the probability that a process with more than one step will yield a defect free product
Brainstorming
Free flow of ideas from a group without criticism or discussion
Brainwriting
Brainstorming on paper that is passed around the group
Nominal Group Technique (NGT)
Free writing period followed by successive sharing around group
Affinity Diagrams
NGT followed by posting on a wall and arranging in logical groups, followed by discussion
Pareto Chart
What is vital, what is trivial. Arrange list of issues in descending order of importance. Assign % to each based upon importance adding all up to 100%.
Left Y-axis shows # of issues, Right Y-axis shows % of importance. X-axis shows categories of issues.
Critical to Quality (CTQ) Tree Diagram
Defines specifically what customer want.
Top level, breaks down into multiple, each of which break down into multiple, etc
Central Limit Theorem
A large of enough population will show an normal mean (xBar). 30 or greater usually
Operating Characteristic Curve (OC)
Graph shows sampling plan probability of accepting a lot with % of defects
Histogram
Graphically compares process variations from machine to machine or person to person
Stem & Leaf Diagram
Creates a graphical representation of data with out a graph. Stem is the first digit (tens, hundreds, thousands, etc) and Leaf are the remaining digits separated by stem. Can show as a curve
Box & Whiskers Plot
Compare two groups of similar data to see mean, median and spread
Probability
P (A) = n/N
A = Event
n = number of chances
N = number of equally likely ways
Binomial Probability Distribution
Probability of Either/Or types of outcome…
P(d) = probability of nonconforming units
n = number in the sample
d = number nonconforming in the sample
p sub o = proportion nonconforming in the population
q sub o = population conforming in the population
P(d) = (n!/(d! * (n-d)!)) * p sub 0 (to the d power) * q sub 0 (to the n-d power)
Poisson Probability Distribution
describe situations that involve events per unit of time or per unit of amount
c = count of an event in a given classification
np sub 0 = average count in the sample
e = 2.718281
P(c) = ((np sub 0) to the c power)/c!) x e to the negative np sub 0 power
Chi-Square Probability Distribution
This distribution is non-parametric, which is a fancy word that means we don’t know about parameters such as means or proportions
chi squared = Sigma((O subi-E subi)squared / E subi)
Create table to show data
Failure Mode and Effects Analysis (FMEA)
Identify impact of failure Rate and Rank each failure activity Determine probability of occurrence Assess probability of detection Determine Risk Priority Number (RPN) for each function Sequence functions by RPN Define recommended action, assign responsibility, and put into motion Follow-up and calculate new RPN
Tensile Strength
The load of a material under which it is expected to break
Decision Making
Define the problem Establish criteria for the decision Establish priorities, weights, and constraints Identify alternatives Evaluate alternatives Select alternative Monitor decision
Linear Regression Analysis
Requires a linear relationship between two variables
Independent variable on the X-axis
Dependent variable on the Y-axis
Multiple Regression Analysis
More than one Independent variable effecting a dependent variable
Cause & Effect Diagram (E&C)
Root cause of a problem
4M, 1P
Machinery, Materials, Measurements, Methods
People
Force Field Analysis
Central Decision, forces on Left are negative, Restrictive Forces, and forces on the Right are positive, Moving Forces
Storyboard
Similar to affinity diagram
Define Communication, Who, What, How
Tree Diagram
Similar to BOM
Why-Why
Keep asking why until you figure out why
Checksheets
Track issues
Scatter Diagrams
Examine relationships between observable events.
Use Trend Tests to find relationship or not
