Types of Error

Random Error

manifest themselves by slight variations in a series of observations made by the same observer under critical conditons

difficult to detect , and intangible, and can almost be not eliminated

Determinate Error

Recur in a constant manner in each of the series of determination.

Detectable and possibly eliminated

Instrumental Error

Caused by non ideal instrument behavior like faulty calibrations, or inappropriate conditons

Method Error

Arise from non ideal chemical or physical behavior of systems

Personal Error

Result from the carelessness, inattention, or personal limitations of the experimenter

Defects

Undesirable characteristic of a product, failure to conform to specification

Variable Defect

Defect that canbe measured directly by an instrument giving dimensions of length, height, thickness, etc

Attribute Defect

Defect that can not be measured directly by instrument, shows conformance or non, like odor or taste

Measurability

Variable and Attribute

Seriousness or Gravity

Critical, Major and Minor

Critical Defect

Defect that may endanger life

Major Defect

Defect that affects the function of the object which makes it useless

Minor Defect

Defect which does not endanger life or will affect the function of the object

Nature

Ocular, Internal, Performance

Ocular Defect

Defect is visible

Internal Defect

Defect is not seen although it is present

Performance Defect

Defect in function

Design Defects

Occurs when the actual design of the product is faulty

Manufacturing Defect

Only affects certain units ir batches of a product, rathrr than all products

Labeling Defects

The product itself is nor necessarily faulty, but it lacks critical warning labels or instructions