18 terms

Quality Final

STUDY
PLAY

Terms in this set (...)

Process Capability
...
Capability Indices
...
X-bar Chart
...
R-Chart
...
p chart
...
u chart
...
c chart
...
ANOVA
Is there any effect of material on uniformity of film thickness of computer chips?
Which material is the best?
Single Factor ANOVA
A test to find out whether differences exist among the means of the populations (i.e., materials) of interest.
If the population means are found different, we compare the population means. (i.e., compare means)
Single Factor ANOVA-First Step
Are the means equivalent?
Partition the total variation in the sample to between and within group variations
Total variance:
= Between group variance + within group variance
In other words, Total sum of squares (SST) =
sum of (Each group mean - Overall mean)2
+ sum (Individual values - Each group mean)2
SST = sum of squares of treatments (SSTR)
+ error sum of squares (SSE)
Single Factor ANOVA: Second Step
Are the means equivalent? Are the between and within group variances are significantly different?
F follows a distribution with degrees of freedom (dof) a - 1, and N - a.
The figure below shows the H0 rejection region for a level of significance where F,a-1,N-a denotes the critical value of F for dof a - 1, and N - a.
Logic of ANOVA Test
Both MSTR and MSE estimatevariation in the data (2 )
If the group means are equal, the ratio MSTR/MSE should be close to 1. (statistically, H0 is true)
If the means are unequal (i.e., H0 is not true), the ratio should be significantly larger than 1, since MSTR would tend to over-estimate 2.
The ratio F = MSTR/MSE
Hence, reject H0 if F = MSTR/MSE is too large
F follows an F distribution with numerator d.f. a - 1, and denominator d.f. N - a.
F is too large, if it is larger than a critical value, F,a-1,N-a.
Single Factor ANOVA: Excel Steps
Go to Data
Go to Data Analysis
Go to Analysis Tools
Click on ANOVA: Single Factor
Select the input range, group's arrangement (i.e., columns or rows, alpha (i.e., significance level), output range
Press ok
Interpret the results
Two Factor ANOVA: Excel Steps
Go to Data
Go to Data Analysis
Go to Analysis Tools
Click on ANOVA: Two Factor with Replication
Select the input range, rows per sample (i.e., number of replication at each factorial level, alpha (i.e., significance level), output range
Press ok
Interpret the results
Pull System
Customer driven - contains clear customer-supplier connections throughout operations!!!
Problems/wastes are eliminated as they surface
Elimination of 7 Forms of Waste (time, effort, material, money)
Overproduction
Waiting (idle time)
Conveyance (material handling)
Processing
Inventory
Defects
Motion
Lean Tools & Techniques
Value Stream Process Mapping (VSM)
Kaizen
5S
Line Balancing
Schedule Leveling
Error Proofing (poka-yoke)
Setup Time Reduction (SMED)
Preventive & Predictive Maintenance
Standardized Work
Visual Management
Reduced Lot Sizes (single piece flow)
Kanban (pull inventory management)
House of Lean: The Toyota Production System
...