Class 10 OM 235

Dimensions of Quality

Provide a framework for evaluating a product or service for the customer’s perspective

Eight Classic Dimensions of product quality

• Performance

• Features

• Reliability

• Conformance

• Durability

• Serviceability

• Aesthetics

• Perceived Quality

Performance

Primary operating characteristics of a product or service

Features

Secondary characteristics or a “bells and whistles”

Reliability

Probability of a project functioning without failure

Durability

How long the product lasts before replacement

Serviceability

Ease, Speed, and cost of repair or maintenance

Aesthetics

How a product looks, feels, sounds, tastes, or smells

Perceived Quality

The customer’s subjective perception

FUNCTIONALITY

• When the product is working, how well does it satisfy the customer?

• Satisfaction usually depends on multiple product features such as performance, aesthetics, even snob appeal

RELIABILITY

• Works without problems as perceived by customers?

• Satisfaction usually depends on multiple product features such as performance, aesthetics, even snob appeal

CONFORMANCE

• Essentially process capability. WARNING: Specification limits may not match customer wants

Process Capability Part 1

• Quality is measured by comparing customer wants and process output

• Customer wants —> design specification ( Upper and lower specification limits USL, LSL)

• Tied tightly to new product development

Process Capability Part 2

• Process output —> process mean and variability

• Standard Deviation, also known as “sigma” or s, is the most common measure of variability in operations

Process Capability Part 3

Process capability increases with the amount of process output that falls within the design specification.

Process output that falls outside are Defects

How to get Process Capability

• To get the Process Capability, we measure, in terms of std. deviations(sigma’s), how close the mean is the nearest(Customer-determined) specification, or more formally

Process Capability

• There is 3-sigma quality process but 6-sigma quality is way better

• 6 standard deviation between the mean and the specification limit on both sides

• More sigma= More control on product= less defects