Performance Rating Formula or Scale in Industrial Engineering
What is Rating in Industrial Engineering?
Different workers perform their job with different efficiencies. Some workers are clever; they learn their job quickly and attain a very high efficiency. Some others may be mediocre and many others may be lenient to learn or may be dull. Thus workers widely vary in their performance. Thus rating is the measure of speed with which an operator works. Rating is the speed of an operator doing a job relative to the observer’s idea of standard pace of work. Rating is thus a comparison of the rate of work observed by a work study executive with the idea of some standard level of working in his mind.
The standard rate is the average rate with which qualified workers are assumed to be able to work provided they are motivated to do the job & if right method of work is applied. Such rate of work is called as standard rating. This standard rate corresponds to 100 in the rating scale.
This is called standard rating; because it is assumed that majority of the qualified workers will be able to achieve such rate of working. If appropriate allowance is provided, a worker can retain standard performance over the whole of working hours.
Scale of Rating in Apparel Manufacturing Industry:
The purpose of rating is to establish the standard time from recorded observed time which a qualified worker can retain throughout her working time & which can be used as a realistic basis for planning, control, target setting etc.
There are several rating scales in use. Here, we shall use British Standard Scale 100 BSI which is also known as 0100 scale. The advantage of this scale is that 0 designates no activity while 100 represent standard rating which is normal for an average qualified worker. The details of the scale are given below.
Rating 
Description 
Comparable Speed 

0 
No activity or 

50 
Very slow clumsy 
2 miles/hr 
3.2 km/hr 
75 
Speedy, purposeful but 
3 miles/hr 
4.8 km/hr 
100 
Speedy, business like 
4 miles/hr 
6.4 km/hr 
125 
Very speedy movement, Dexterity and 
5 miles/hr 
8.0 km/hr 
150 
Exceptionally fast 
6 miles/hr 
9.6 km/hr 
Basic Time Calculation in Industrial Engineering:
Basic time is the time required by a qualified operator to complete a job had she worked at standard performance (or at 100 % rating). Basic time is obtained by multiplying observed time with the rating of the worker.
Thus, Basic time = Observed Time X rating of the operator
Example:
For example, an operator attaches topcenter to the left front, her observed time shows 28 seconds. Work study executive considers her of 80% rating. Calculate Basic time of the operation.
Answer:
Observed Time: 28″
Rating of the operator: 80%
So,
Her basic time =Observed time x her rating = 28 “x 80% = 28″x 0.8. =22.4”