Operations Management and Strategic Management · Control Measures - Time and Motion Study, Method Study, Work Study

Work Measurement and Time Study for CMA Intermediate

Updated 10 October 2026 · Fact-checked

Work measurement finds the time a qualified worker needs to do a job at a defined performance level. In a stopwatch time study, you record observed times, apply a rating to get basic time, add allowances to get standard time, and use it for planning and costing.

Understand Work Measurement and Time Study

Work measurement is the application of techniques to establish the time a qualified worker takes to carry out a specified job at a defined level of performance. It is the second part of work study. Method study decides how the job should be done. Work measurement decides how long it should take.

The result is the standard time. Managers use it for production planning, scheduling, labour cost standards, incentive wages, manpower planning and comparing actual output with what was expected.

Time study is the most common technique. An observer times a job with a stopwatch over several cycles. The job is first broken into elements, which are small, easily identified parts of the work. Each element is timed and the observer also judges the worker's speed against a standard. That judgement is called rating.

Observed time is not standard time. The worker may be faster or slower than the standard pace, so you adjust by rating. Even a standard worker needs rest, personal needs and some unavoidable delays, so you add allowances. This gives the chain: observed time, basic time, standard time.

Other techniques are work sampling (many random instantaneous observations to find the share of time spent on activities), synthesis from standard data, analytical estimating, and predetermined motion time systems (PMTS), which use published time values for basic motions instead of a stopwatch. Time study differs from motion study: time study measures duration, while motion study analyses the movements to remove wasteful ones.

Key rules to remember

Basic time (normal time): Basic time = Observed time × Rating ÷ Standard rating; If standard rating is 100, basic time = observed time × rating ÷ 100. Rating above standard increases basic time.
Standard time: Standard time = Basic time + Allowances; If allowance is a percentage of basic time: Standard time = Basic time × (1 + allowance %).
Allowance as percentage of total (gross) time: Standard time = Basic time ÷ (1 − allowance % of standard time); Use this only when the question states the allowance as a percentage of the standard (total) time.
Number of observations (sample size): Number of observations is chosen from the variation seen in a trial set of readings; More variable elements need more readings. Use only the method given in the question.
Work sampling: percentage of activity: Activity % = Observations of the activity ÷ Total observations × 100; Time for the activity = Activity % × total time period studied.
Standard output: Standard output per period = Available time ÷ Standard time per unit; Use consistent units, such as minutes per unit and minutes per shift.

How to solve Work Measurement and Time Study questions

Use this order for any question on time study, standard time or work sampling. Do not skip the rating step when it is given.

1Read what is asked: observed time, basic time, standard time, output or work sampling percentage.
2Collect the observed time per element. If several readings are given, take the average unless told to remove abnormal readings.
3Apply rating to each element: basic time = observed time × rating ÷ 100.
4Add the basic times of all elements to get basic time per cycle. Include only elements that occur every cycle, or convert occasional ones to a per-cycle basis.
5Add allowances as stated, noting whether they apply to basic time or to total time.
6Compute standard time per unit, then standard output or labour cost if required.
7For work sampling, count observations by activity, convert to percentages and apply to total time.
8Write each step clearly with units, and state the final answer with a one-line interpretation.

Quickest way: Rating-then-allowance shortcut

When to use it: Use for numerical questions where one or more elements are timed, with a rating and a percentage allowance.

Multiply each average element time by its rating factor, such as 110% = 1.10.
Add all to get basic time.
Multiply by (1 + allowance %) if allowance is on basic time.
Divide into the available minutes to get output.
Check that the standard time is larger than the basic time. If not, you have made an error.

Common mistakes in Work Measurement and Time Study

Treating observed time as standard time.
Students forget rating and allowances are separate steps.
Fix: Always write the chain: observed time, basic time, standard time.
Applying rating in the wrong direction.
Confusion about whether a fast worker's time should rise or fall.
Fix: A worker faster than standard has a rating above 100, so basic time is higher than observed time.
Adding allowances before rating.
Students add percentages in a single step.
Fix: Rate first to get basic time, then add allowances to that basic time.
Mixing allowance on basic time with allowance on total time.
The wording is overlooked.
Fix: If allowance is a percentage of standard time, divide basic time by (1 − allowance rate).
Confusing time study with motion study and method study.
All three belong to work study and sound alike.
Fix: Method study improves the way of working, motion study analyses movements, and time study measures duration.
Treating work sampling as continuous observation.
It is compared with stopwatch study.
Fix: Remember it uses random, instantaneous observations and gives percentages of time, not cycle times.

Worked examples

Example 1

A job has two elements. Average observed times are 4 minutes and 6 minutes. Ratings are 110 and 90 respectively. Allowances are 10% of basic time. Find the standard time per unit and the standard output in an 8-hour shift.

Show the solution

Element 1 basic time = 4 × 110 ÷ 100 = 4.4 minutes.
Element 2 basic time = 6 × 90 ÷ 100 = 5.4 minutes.
Total basic time = 4.4 + 5.4 = 9.8 minutes.
Allowance = 10% × 9.8 = 0.98 minutes.
Standard time = 9.8 + 0.98 = 10.78 minutes.
Shift time = 8 × 60 = 480 minutes.
Standard output = 480 ÷ 10.78 = 44.53 units, about 44 complete units.

Answer: Standard time is 10.78 minutes per unit; standard output is about 44 units per 8-hour shift.

Example 2

In a work sampling study, 400 random observations of a machine were made. It was found working in 300 observations, idle in 60 and under repair in 40. The study covered 160 hours. Find the percentage and hours for each state.

Show the solution

Working % = 300 ÷ 400 × 100 = 75%.
Idle % = 60 ÷ 400 × 100 = 15%.
Repair % = 40 ÷ 400 × 100 = 10%.
Check: 75 + 15 + 10 = 100%.
Working hours = 75% × 160 = 120 hours.
Idle hours = 15% × 160 = 24 hours.
Repair hours = 10% × 160 = 16 hours.

Answer: Working 75% (120 hours), idle 15% (24 hours), under repair 10% (16 hours). Idle time of 15% is a target for investigation.

Exam tips

In MCQs, check whether the allowance is on basic time or total time before calculating.
Show each element's rating step separately in written answers. Step marks are given for method.
For theory, use the sequence: select job, record, examine, measure, compile, define standard time.
Be ready to give differences between time study and work sampling, and between stopwatch study and PMTS.
State the units, minutes or hours, at each step.

Practice questions from Control Measures - Time and Motion Study, Method Study, Work Study

Work Measurement and Time Study in other exams

The same ground in other exams, if you are preparing for more than one or want another angle on it.

Work Measurement and Time Study: frequently asked questions

What are the steps of a stopwatch time study?

Select the job, record details of the method and conditions, break the job into elements and time each over several cycles. Then rate the worker, compute basic time, add allowances and fix the standard time.

What is the difference between time study and motion study?

Time study measures how long a job should take at a standard pace. Motion study analyses the body movements used in the job to remove wasteful ones. Time study gives a standard, while motion study improves the method.

What is work sampling?

Work sampling makes many random instantaneous observations of workers or machines and records their activity. The share of observations in each activity estimates the share of time spent on it. It suits long, irregular or non-repetitive jobs.

What is a predetermined motion time system?

It is a technique that breaks a job into basic human motions and assigns each a published time value. Adding the values gives the job time without a stopwatch. It can be used before the job exists, at the planning stage.