1. Introduction 1

2. Direct Time Study 1

2.1 Introduction 1

2.2 The Worker Factor 1

2.3 Rating 1

2.4 Allowances and Time Standard 1

2.5 Issues with Time Study 1

3. Work Sampling 1

3.1 Introduction 1

3.2 Sampling and Confidence Intervals 1

3.3 Random Observations 1

3.4 Advantages of Work Sampling 1

3.5 Disadvantages of work sampling 1

4. Predetermined Time System (PTS) 1

4.1 Introduction 1

4.2 The MTM System 1

4.3 Advantages of Predetermined Time Systems 1

4.4 Criticisms of Predetermined Time Systems 1

5. Standard Data System 1

5.1 Introduction 1

6. Conclusion 1

7. References 1

1. INTRODUCTION

Work measurement is a series of techniques employed to evaluate the time needed for completion

of a task by an average human worker. This evaluated time is called the Standard Time of the task.

The standard time serves as a benchmark for productivity. Standard time is the time required by a

qualified and well-trained person working at a normal pace, to do a specified task. Any worker who

exceeds the standard time set for a particular task is said to be working slowly. Thus, this system

enables organizations to get a fair idea of the rate at which their employees are working, and

whether they are working fast enough or not. Standard time does include a certain amount of

allowance, to provide for a worker’s personal needs, fatigue and unavoidable delays during the

shift. This is an important aspect, since employees are paid according to their work output in hours

in many organizations. Work measurement is often also called time study, although the areas of

concern in each case is slightly different. Work measurement is largely concerned with human work

output, while time study also considers any automated work output. Work measurement consists of

four techniques, namely

• Direct Time Study

• Predetermined Motion Time System

• Standard Data System

• Work Sampling

Time study or work measurement has several important uses. It helps in the determination of

schedules and the planning of work. It can aid in determining standard costs. It is fairly helpful in

determining the amount of wage that needs to be paid for labor, and helps an organization to ensure

that it is paying its employees appropriately for their labor. Time standards serve in determining the

amount of staff needed to accomplish a particular amount of workload. Time standards also serve

the highly important objective of helping organizations evaluate their employees’ performance. The

all-important objective of determining whether an employee has put in a “fair day’s work” can be

determined simply by analyzing the sum of the standard times of all the tasks accomplished during

the day, and checking where it stands, relative to the total number of hours in a day’s shift. If it is

fairly less than the total number of hours in a day’s shift, the employee is said to be working too

slowly.

2. DIRECT TIME STUDY

2.1 Introduction

Direct time study, as its name suggests, is the direct measurement of the time taken by an

operator/worker to complete a certain task. It involves the subdivision of the entire task into the

various work elements that it is composed of, and measuring the time taken to accomplish each

work element. The total operation time is then calculated as the sum of the individual work element

times. A rating is then given by the evaluator, which is used to calculate the normal time that is

required for completion of the task. Normal time is defined as the time required to accomplish a

certain task by an average worker, working at a normal pace, but without any allowances. It

represents the time taken to complete the task alone. The standard time for the operation is then

computed by adding any allowances as required to the normal time. In this way, we can compute

the maximum allowable time for completion of an operation, beyond which the worker is said to be

working at a lower than normal pace. The equipment needed for this study are a time measuring

device such as a stopwatch and an observation board with a time study sheet, to chart the times

required for completion of each of the component work elements. An alternative approach is to film

the entire operation using a video camera, and analyze the number of frames needed to complete the

entire task or each of the work elements. Since we know the frame rate of the camera, we can

calculate the time taken, accurately.

Selection of the job for the time study is an important initial step. There are various reasons why a

certain job/operation might need a time study performed on it. Some of them are listed below

• The job in question is a new one, for which a time standard has not yet been determined.

• There has been a change in the method used for the operation or materials, which could affect the

time standard

• A particular operation appears to be a bottleneck, holding up several other operations because it is

taking too much time.

• The cost of a particular job appears to be excessive, and a study is needed to determine if the

method is inefficient.

In the event that a time standard must be defined for the first time, it is advisable to ensure that the

best method to accomplish the task has already been developed, before the time study is performed

on it. Hence, a comprehensive study of the process is needed.

2.2 The Worker Factor

Employees present one of the biggest challenges with Direct Time Study. One of the most

important steps before performing a time study is obtaining the consent of the foreman and/or

workers involved in the operation. This is important, since the purpose of a time study is not fairly

obvious at first. The entire objective of the time study could be misunderstood, unless it is carefully

explained to everyone. Anyone performing a direct time study must first obtain consent from the

foreman and/or the workers, and explain to them clearly the objective of the time study, what the

process would involve, and seek their consent before going on with the process.

The person performing the study should position himself appropriately for performing the time

study. He should be so placed that he can see everything the operator does, including his hand

motions, without interfering with his movements or distracting his attention. He should not stand

directly in front of him, or so close to him that the worker feels that he has “someone standing over

him”, which has been a frequent complaint against time study. A recommended position for the

time study man is to the side of the operator, and to the rear, about 2 meters away. However, the

actual position will be dictated by the actual operation. On no account should the time study be

attempted from a concealed position, without the operator’s knowledge. It is also recommended

that the time study man stands while performing the time study, since the worker could get the

impression that he is doing all the work while the time study man simply sits and watches him,

timing him all the while.

Most workers tend to settle down to their normal working pace. However, there are cases,

especially when workers are nervous, where the workers attempt to work unnaturally faster, thus

fumbling more and possibly working slower than their normal rate. In such an event, the time study

must be stopped and the time study man should talk to the worker and ensure he is calm and

composed before resuming the study again.

2.3 Ratings

Ratings are a significant part of time study. Ratings help in determining the normal time for an

operation, and they represent the rate at which a worker is working. Ratings are a comparison

between the operator’s speed or tempo, and the observer’s own concept of normal performance and

rate. Hence, it is a matter of judgment on the part of the time study analyst, and since these ratings

have an impact on the time standards set, which later have an impact on incentives, they must be

appropriately given, to ensure the workers are not overworked, while also ensuring that the

management is not overpaying their employees. It is a balance between management and labor.

Selection of workers for the time study has a significant impact on the rating system. It must be

ensured to the greatest extent, that only qualified workers are selected for the study. Very fast or

very slow workers must be left out of the study.

2.4 Allowances and Time Standard

Normal time is calculated as the product of observed time and the rating. This time represents the

amount of time taken by an average worker, working at a normal pace, to complete the task.

However, this does not account for various delays, such as personal needs of the worker, fatigue,

and possible delays in the process due to breakdowns, etc. To compensate for such delays,

allowances are calculated and added to the normal time, to give what is known as the standard time

which represents the time required for completion of the task, inclusive of delays.

Allowances are applied as a percentage of normal time. The standard time for the operation is

determined as the sum of the normal time and allowances, obtained from the product of normal time

and the percentage of allowance.

2.5 Issues with Time Study

Time study has many latent benefits that come with it. One such benefit is that it is highly versatile

and can be easily applied to any operation. However, there are many disadvantages to applying the

time study method for work measurement. Some of these are described below.

1. Time study is a highly tedious process, from the start to the end. It involves a comprehensive

study of the process and needs to be performed again for a change in process. Taking

measurements of the operator is also highly tedious, especially when the sample size needed is

fairly large.

2. This process cannot be applied to situations when the job cycle time is very high. It can also not

be applied to jobs that are highly complex and have several work elements, since it becomes

fairly cumbersome to note element times for such processes

3. Time study involves obtaining consent from the workers first, and explaining the entire process

to them. It could also cause workers to attempt to work slower than their normal pace during the

time study in order to prevent the time standard from being set too small. Alternately, workers

could also end up attempting to work faster than normal to ensure that they’re not accused of

being too slow. Accurate judgment on the part of the observer is needed in such cases.

4. This system depends heavily on the rating system. Ratings given are based on the judgment of

the observer, and thus, any error in judgment on the part of the observer could result in the time

standard being set too low, causing the workers to be overworked, or the converse where

workers are overpaid and underworked.

5. In order to ensure that the ratings supplied are accurate, the analyst should be fairly experienced,

or have undergone training in assigning ratings.

2.6 Advantages of Time Study

1. Direct time study is fairly versatile, since it only involves the use of a time measuring device

such as a stopwatch, and time is measured directly.

2. A description is provided of the method along with a sketch. This helps understand the

conditions and nature of the task being performed, even in the future when referencing past time

study records.

3. Direct time study is applicable to a single subject, unlike work sampling which is better suited

for groups of subjects.

4. Direct time study provides a greater detail about the capabilities of individual workers.

5. Direct time study does not depend on previously taken data, unlike the Standard Data System. It

is thus, more reliable.

6. Direct time study is suited for systems where the number of standards to be set is small in

number.

7. It is fairly simple to explain direct time study process to workers and management.

3. WORK SAMPLING

3.1 Introduction

This system was first used by L. H. C. Tippett in the British textile industry in 1940. It is a highly

efficient system through which, needed information can be obtained in less time, and at a lower

cost, compared to other methods of work measurement. It is also known as “activity sampling”,

“ratio-delay study”, “random observation study”, “snap-reading method” and “observation ratio

study”. It is based on the laws of probability. A sample taken at random from a large group tends to

have the same pattern of distribution as the large group or universe. If the sample is large enough,

the characteristics of the sample will differ little from the characteristics of the group. Sample is the

term used for this small number, while population or universe is the term used for the large group.

Sampling is the process of obtaining and analyzing only a small part of the universe.

3.2 Sampling and Confidence Intervals

Work sampling is based on probability. Probability is defined as the extent to which an event is

likely to occur. It can be calculated by analyzing the fractional extent of occurrences of the event in

question, within a given sample. The probability of an event occurring tends to get more accurate

with greater sample sizes. However, since it is impossible to take a fairly large number of samples,

a sample as large as possible is taken. The level of confidence we have of the sample being

representative of the population is expressed as a confidence level. The concept of confidence levels

involves the normal distribution. Over repeated observations, it is assumed the distribution of

observations would follow a normal distribution. The confidence levels are expressed as integer

multiples of the standard deviation σ of the data. (1σ, 2σ, 3σ). The associated level of confidence

depends on the spread of data considered. A deviation of 1σ corresponds to 68% of the area of the

curve, centered about the mean. Similarly, a deviation of 2σ corresponds to 95% and 3σ

corresponds to 99.7%. Thus, at a 99.7% confidence level, most of the data points will have a spread

of at the most 3σ.

The determination of confidence levels is important in determining the sample size needed for the

study. Since the standard deviation depends on the sample size, an appropriately large sample must

be taken to ensure that we achieve the desired level of confidence.

3.3 Random Observations

The next step in work sampling is to take observations. An important factor is that the observations

must be random. This can be ensured by using a table of random numbers to determine times for

observation taking. At each of these times now shortlisted, an observation is made of the state of the

process (working/idle), and noted. The proportion is determined next. This proportion is the ratio of

the number of observations in which the state that we are interested in has occurred (based on our

objective, such as number of times machine is working), to the total number of observations made.

This proportion is calculated at the end of each day. Control limits are then set, according to the

requirement, and a study is made to see if the process is working as required or not. The time taken

for the process can be determined from the product of the proportion of the readings in a day that

the process was not idle, and the total time for a day’s shift. The standard time can then be

calculated by taking the product of time taken, and an average performance index for the worker.

3.4 Advantages of Work Sampling

1. It is easier to measure processes that have long cycle times or are costly to measure, by work

sampling.

2. A study can be made of several operators simultaneously, using work sampling. Time study,

however, requires an analyst for each operator analyzed.

3. It requires fewer man-hours and less costs to do a work sampling study.

4. Observations are taken on a day-to-day basis or week-to-week basis, thus decreasing the effect

of day-to-day variations or weekly variations on the results

5. A work sampling study may be interrupted at any time without affecting the results.

6. A work sampling study is far less fatiguing and tedious than a direct time study, since the study

is not performed continuously.

7. Workers being observed tend to prefer work sampling to direct time study to avoid being

monitored continuously.

8. A stopwatch is not needed for a work sampling study

3.5 Disadvantages of work sampling

1. Work sampling is not economical for studying a single operator or machine, or studying

operators or machines spread out over large areas.

2. Time study permits a finer breakdown of activities and delays than is possible with work

sampling. Work sampling does not provide as much detailed information as is available from a

time study.

3. Management and workers may not understand statistical work sampling as readily as they do

time study.

4. A work sampling study made of a group represents the average of the capabilities of the entire

group, and does not highlight individual capabilities.

5. A work sampling study is effective only when the sample size is calculated effectively for the

desired level of accuracy, and the same number of observations are taken. It is also very

important for the observations to be taken at random times. If any of these steps are ignored or

compromised on, the work sampling study is not entirely effective.

4. PREDETERMINED TIME SYSTEM (PTS)

4.1 Introduction

Time standards for an operation can be determined by direct time study, which involves direct

measurement of the time taken for the process. However, another approach for determining

standard times is to use predetermined times. The Predetermined Time System consists of a set of

predetermined time data and a system for subdividing any manual operation into motions, body

movements or human performance, and assigns to each the appropriate time value. The beginnings

of PTS stretch back to the study of Frank B. Gilbreth, who first classified human motion into

“therbligs” which were the basic building blocks of most standard hand and body motions

encountered in a process. However, the first Predetermined Time System was established by A. B.

Segur in 1927, calling the system Motion Time Analysis. Segur stated that “within practical limits

the time required for all experts to perform true fundamental motions is a constant”.

Following the Second World War, however, a system called the Methods-Time Measurement

(MTM) was developed, that later went on to become one of the most widely used systems for work

measurement. MTM was developed by H. B. Maynard, G. J. Stegemerten and J. L. Schwab, who

worked on the system at the Westinghouse Electric Corporation in the United States. The

significance of the MTM system is that the findings were publicly published and are made freely

available to everyone.

4.2 The MTM System

The Methods-Time Measurement (MTM) system is one of the most widely used Predetermined

Time Systems. It involves dividing human motion into various categories such as Reach, Move,

Grasp, Apply Pressure, Position, Turn, etc. For each category of motion, predetermined times are

supplied, based on the conditions of the work. For instance, in the case of Reach, there are 5 classes,

based on the nature of the reach. ‘A’ represents reaching for an object at a fixed location, ‘B’

represents reaching for an object whose location may vary from cycle to cycle, ‘C’ represents reach

for an object that is jumbled with other objects in a group, ‘D’ represents reaching for a very small

object or where accurate grasp is needed, and ‘E’ represents reaching to an indirect location, usually

for body balance. For each subcategory, times are provided, based on the distance of reach

travelled. Similarly, for other hand and body motions, times are provided for the various scenarios

that may occur. Thus, if the entire operation is divided into the various motions presented in the

MTM system, it is possible to determine the time that would be needed to perform each work

element, and thus, the total time needed to perform the operation.

4.3 Advantages of Predetermined Time Systems

1. Predetermined Time Systems eliminate the need for measuring time by a stopwatch or by

sampling.

2. It is possible to determine the standard time for an entire operation even before the operation has

begun or while it is at a design stage. This facilitates the development of a method that is cost

effective.

3. The Predetermined Time System is fairly easy to apply and does not require any tedious effort

on the part of the analyst in measuring time.

4. They are useful for determining standard times for very short, repetitive cycles such as assembly

work in the electronics industry.

5. Ratings are not required in this system in any way, since they are built into the system. Thus,

there is no requirement of the judgment on the part of the analyst in evaluating the pace of the

operator.

4.4 Criticisms of Predetermined Time Systems

1. Predetermined Time Systems are rather complicated, and are not easy to learn. A work study

man requires a good deal of practice before he can apply it correctly

2. PTS does not consider any special cases of motion such as a case where a full cup and an empty

cup of liquid would be given the same time for movement. However, in the case of the full cup,

the motion has to be slower, especially when care must be taken to avoid spilling the liquid.

3. It is sometimes considered invalid to add up times for individual motions as proposed by the

PTS, since motions will be influenced by the ones preceding them and following them.

However, this limitation was overcome in some systems such as the MTM system.

4. Direction of motion influences the time taken. For instance, moving in one direction might

taken more time than in the reverse direction if there is an incline in one of the directions.

5. STANDARD DATA SYSTEM

5.1 Introduction

This system employs a database of normal time values, organized by work elements, in order to

establish the time standards for a particular task/operation. Normal time values for the work

elements are usually compiled from previous direct time studies (DTS). Unlike those previous time

studies, it is not necessary to directly observe the task in order to set a time standard using a

Standard Data System (SDS). Accordingly, standards can be determined for a task before the job is

running.

When using the Standard Data System, the analyst lists the work elements that would be required

for a new task, specifying the details and parameters that will affect the time to accomplish the

element. By adding the appropriate allowance factor, we can compute the standard time for each

element. Thus the standard time for the entire operation can be computed from the sum of the

standard times of individual component work elements.

To apply a Standard Data System, the database of normal times for work elements must initially be

developed. This may be done using Direct Time Study and/or Predetermined Time Systems. When

a Predetermined Time System (PTS/PMTS) is used to develop times for a standard data system, it is

for either of the following purposes:

1. to supplement the database of DTS values because some of those data values are missing, or

2. to develop the SDS database of work element normal times from the basic motion element times

in the PTS/PMTS.

Thus, a Standard Data System is considered to be a macroscopic approach to Work Measurement,

while PTS/PMTS is considered a microscopic approach.

5.2 Applications of Standard Data Systems (SDS)

1. Standard Data Systems can be applied to work facilities where several of the tasks performed

are similar in nature.

2. This system is best suited for medium production of batches.

3. It can be applied in situations where a large number of standards are to be set. In such cases, the

SDS method proves to be more efficient, compared to DTS and PTS/PMTS, especially when

the analysts available on hand are less in number.

4. Standard Data Systems can be used to establish time standards for an operation even before it

has begun operation.

5.3 Advantages of Standard Data System

1. Standard data systems require far less time for setting time standards compared to direct time

study.

2. Standard data systems serves as a fairly cost efficient method when the number of standards

required to be set are high in number, since it compromises on the cost of additional analysts

that would otherwise be required by other methods such as direct time study.

3. Standard time can be set before commencement of production using Standard Data Systems.

This is not possible with direct time study since it requires direct observation. This helps in cost

estimation and also can be used as an input to other planning and scheduling programs such as

Material Requirement Planning (MRP) and Enterprise Resource Planning (ERP).

4. Performance ratings are factored into the system, and hence there is no need for them. This

eliminates the need for judgment on the part of the analyst.

5. Standard Data Systems tend to be more consistent as compared to direct time study since it is

created from the average of several time studies made earlier.

5.4 Disadvantages of Standard Data System

1. Developing a Standard Data System requires considerable time and effort. This system is thus

not economically feasible when the number of standards to be set are relatively low.

2. Standard data system employs a database built from previous work measurement data taken

through time study or predetermined time studies. Hence, the company must have access to such

data and should ensure the integrity of the data before carrying out the study. If the data is

biased in a certain way, then the results will also be biased in that direction.

3. A standard data system is designed with a certain scope of coverage in mind. It is developed

from data from a defined family of tasks and its applications are limited to setting time

standards for new tasks in that same family. In that sense, Standard Data Systems are slightly

limited in nature.

6. CONCLUSION

Work measurement forms an integral part of work study, and is highly essential for companies from

a managerial perspective. The importance is realized from the fact that work measurement gives an

indication of the level of output, in terms of time, from the workforce in an organization, and since

this is often directly related to compensation and incentives, it is essential to ensure that the method

of work measurement used is efficient and appropriate. The ultimate objective is to obtain the

standard time for an operation, and there are four basic methods that are in use for this purpose. The

applicability of each method varies as per the work conditions.

Direct time study is a highly versatile method that can be applied in situations where the cycle time

is neither too small nor too long. However, direct time study is highly tedious in nature, and

requires worker consent prior to performing the study. Work sampling on the other hand, can be

applied in situations where the cyele time is very long, and is far less tedious. The Predetermined

Time System (PTS/PMTS) is useful when the cycle time is very small, and has the advantage that it

is less tedious than direct time study, and the work measurement data can be obtained before the

operation has commenced, thus giving an idea of the costs involved. A similar case is with the

Standard Data System, since it can be accomplished before the process has begun and takes less

time as compared to other methods. The SDS and PTS/PMTS systems are virtually similar in

nature, but with different approaches, one being microscopic in nature and the other being

macroscopic in nature. However, since SDS depends on previous data, it is essential to ensure the

integrity of the data to prevent the data obtained from the SDS to be biased.

The objective of obtaining the standard time for the various operations at an organization can be

obtained through any of the four methods listed above and it is up to the management to decide the

method that is best suited to their scenario, by analyzing the various advantages and disadvantages,

and applicability of each method.

7. REFERENCES

1. Barnes, R. M. “Motion and Time Study. Design and Measurement of Work”. 7th ed. John

Wiley & Sons, Inc.

2. International Labour Office. “Introduction to Work Study”. 3rd ed. International Labour Office,

Geneva. 1981.

3. Groover, M. P. “Work Systems and the Methods, Measurement, and Management of Work”.

Prentice Hall. NJ. 2007