Measurement is a process of assigning a numeric value to a property. The property can be a length, weight, etc. The Value assigned is defined as the Measurement Value.
When we try to describe a length without a measurement, we need to define as short, long etc. But when we describe a length using a measurement we can specify as 20 Meters, 5 Cm etc.
Measurement basically falls into two categories
- Attribute Measurement
- Variable Measurement
When the measurement process result is in “Ok, Not Ok” format the measurement process is termed as Attribute Measurement.
Example: When you check if the pan on the stove has turned hot or not by dropping few drops of water, the result of the inspection done is that “pan is Hot or the Pan is not Hot”. The exact temperature of the pan is not known.
Similarly in Industry when we do the Inspection of a Diameter of the Hole produced on the component using a Plug gauge the result of the inspection is either the Hole Diameter is OK or the Diameter is Not Ok. the exact diameter of the hole is not known.
Example of Attribute measurement
- Plug Gauges
- Ring Gauges
- Receiver gauges
When the measurement process result is in a numeric value the measurement process is termed as Variable Measurement.
Example: When you inspect the weight of the rice bag on a weighing scale the result of the inspection is arrived in a numerical value such as 5 Kg , 2000 Grams etc.
In Industries When we do the inspection of a diameter of the Hole produced on the component using a Vernier Caliper the result of the inspection process is arrived in a numerical value such as 25.14 mm, 14.36 mm etc.
The results can be compared with the specification to decide whether the machined part is Accepted or Rejected.
Example of Variable Measurement
- Vernier Caliper
- Dial Gauges
Additional Books to read on this Topic: