Allowances, Standard Data, and Predetermined Motion-Time Systems

Introduction

Work measurement converts an observed method and performance level into a time standard. A sound standard is not simply the fastest observed time. It is the time required by a qualified worker, working at a defined pace, using an approved method, under specified conditions, with appropriate recognition of unavoidable human and operational variability. This chapter examines three closely related instruments of advanced work measurement: allowances, standard data, and predetermined motion-time systems (PMTS).

Allowances protect the validity and fairness of a standard by recognizing personal needs, fatigue, unavoidable delays, and exceptional features of a task. Standard data allow an organization to reuse previously established time values rather than conduct a new study for every similar job. PMTS establishes times by analyzing basic human motions—such as reaching, grasping, moving, positioning, and releasing—before or independently of production observations. The principal systems considered are Methods-Time Measurement (MTM) and Maynard Operation Sequence Technique (MOST).

These tools are powerful, but they are not interchangeable. Allowances address time that should be included in a standard; standard data provide a structured repository of known time elements; PMTS predicts or analyzes task time from a defined method. Professional application requires technical competence, employee consultation, ergonomic judgment, statistical discipline, and governance over how standards are used.

Learning Objectives

By the end of this chapter, the reader should be able to:

1. Distinguish normal time, standard time, observed time, and rating-adjusted time.
2. Establish personal, fatigue, delay, and special allowances using defensible assumptions.
3. Explain the difference between an additive allowance and a percentage allowance.
4. Design and maintain a standard-data system.
5. Explain the logic and coding structure of PMTS.
6. Apply MTM and MOST appropriately and recognize their limitations.
7. Select a work-measurement technique for a managerial or engineering situation.
8. Evaluate the ethical, ergonomic, and governance implications of time standards.

1. The Architecture of a Time Standard

A typical direct time study begins with observed cycle times. Because observed performance includes worker pace, the analyst applies a performance rating to estimate normal time. Allowances are then added to obtain standard time.

The general relationship is:

where:

• N = normal time per cycle;
• Ō = average observed time per cycle, in minutes or seconds;
• R = performance rating expressed as a decimal, such as 1.10 for a worker judged to perform 10% above the defined normal pace.

The equation assumes that the observations represent the approved method and that the rating is applied consistently. If rating is reported as a percentage, 110% must be converted to R = 1.10.

If an allowance is expressed as a proportion of working time, standard time is commonly calculated as:

where S is standard time and A is the total allowance fraction. This formulation is appropriate when allowance is defined as the proportion of the available shift that is legitimately unavailable for productive work. It ensures that the allowance is included in the standard-time base.

An alternative convention is to add a percentage directly to normal time:

where a is an additive allowance percentage. These two conventions are not numerically identical. For example, a 15% factor using the first convention gives S = N ÷ 0.85, whereas an additive 15% factor gives S = 1.15N. An organization must define which convention it uses; mixing them produces systematically biased standards.

Worked example 1: from observed time to standard time

A packaging operation has an average observed cycle time of 2.40 minutes. The analyst assigns a performance rating of 95%. Personal allowance is 5%, fatigue allowance is 4%, and unavoidable delay allowance is 3%. The allowances are defined as portions of available working time.

First calculate normal time:

The total allowance is:

Therefore:

The standard is approximately 2.59 minutes per cycle, assuming the method, rating, and allowance definitions are valid. If the organization instead defines allowances additively, the result would be 2.28 × 1.12 = 2.5536 minutes. The difference illustrates why the convention must be documented.

2. Allowances: Purpose and Classification

An allowance is an increment to normal time that recognizes conditions not represented adequately by the basic performance time. It should not be used to conceal poor methods, defective equipment, unrealistic production targets, or inadequate staffing. Such problems require engineering or managerial action.

2.1 Personal allowance

Personal allowance recognizes time required for essential personal needs, such as drinking water, using restroom facilities, and brief personal adjustment. It is not a reward for slow work and should not be used to discriminate among workers. A personal allowance may be established through organizational policy, work sampling, historical data, or negotiated labor arrangements. Climate, clothing, gender-neutral access to facilities, pregnancy, disability accommodation, and local regulations may affect the appropriate value.

A fixed percentage can be convenient, but it may be inappropriate when work conditions vary substantially. For example, a hot process, protective clothing, or restricted access to hydration may require a larger allowance or engineering controls rather than merely a larger standard.

2.2 Fatigue allowance

Fatigue allowance recognizes recovery from physical or mental effort and from environmental stressors. Its basis should include:

• force and repetition;
• awkward posture and static muscular loading;
• vibration;
• heat, cold, noise, illumination, and air quality;
• visual and cognitive demand;
• load handling and walking;
• shift length, recovery opportunities, and work–rest organization.

Fatigue allowance is not a substitute for ergonomic redesign. If a workstation imposes excessive force or harmful posture, the preferred response is to reduce the hazard through design, engineering controls, job rotation where appropriate, and improved work organization. Allowances should never legitimize exposure to unacceptable risk.

2.3 Delay allowance

Delay allowance covers unavoidable interruptions that are outside the worker's control but are part of the normal operating environment. Examples include waiting for material replenishment, minor equipment adjustment, inspection decisions, or a shared tool becoming available. Delays caused by preventable planning failures, chronic breakdowns, poor quality, or understaffing should be measured and addressed as process losses rather than automatically embedded in the standard.

Delay may be estimated using work sampling. If observations show that a worker is in an unavoidable delay state in x of n random observations, the estimated delay proportion is:

where p̂ is the estimated proportion. Random observations should be genuinely distributed over the operating period, and the categories must be mutually exclusive and operationally defined. A confidence interval may be required when the estimate is used for a consequential standard; a point estimate alone can create false precision.

2.4 Special allowances

Special allowances recognize legitimate conditions not covered by general personal, fatigue, and delay allowances. Examples include:

• start-up and shut-down activities;
• cleaning, lubrication, and tool changes;
• setup or changeover;
• learning or training periods;
• interference when one worker serves several machines;
• temporary conditions during a product introduction;
• small-lot or infrequent activities;
• contingencies specifically authorized by policy.

Special allowances should be separately identified, quantified, and periodically reviewed. Hiding them in a general percentage makes standards difficult to audit and can prevent management from improving the underlying process.

2.5 Policy principles for allowance setting

A defensible allowance system has five features. First, categories are clearly defined. Second, values are supported by observation, ergonomic assessment, historical evidence, or policy. Third, the method distinguishes controllable from uncontrollable losses. Fourth, workers and relevant representatives can challenge unrealistic assumptions. Fifth, allowances are reviewed when equipment, product, staffing, environmental conditions, or work organization changes.

3. Standard Data Systems

Standard data are organized time values for recurring work elements, motions, machine actions, or conditions. A standard-data system may contain values derived from direct time studies, PMTS analyses, machine specifications, or validated historical observations. It is more than a table of times: it is a controlled knowledge system linking time values to methods and conditions.

3.1 Structure of a standard-data system

A useful database record generally contains:

The element definition is critical. “Pick part” is too vague unless the database specifies part orientation, location, reach distance, container condition, and whether inspection or repositioning is included.

3.2 Developing standard data

Development normally follows these steps:

1. Define the scope, product family, method, and time unit.
2. Select representative operations and qualified workers.
3. Break work into repeatable elements with observable boundaries.
4. Collect sufficient observations under normal operating conditions.
5. Remove or separately classify abnormal events rather than deleting inconvenient data without explanation.
6. Apply performance rating where direct-study data require it.
7. Establish allowances according to policy.
8. Analyze relationships between time and causal variables, such as quantity, distance, or batch size.
9. Validate the values on independent jobs.
10. Publish, train users, and control revisions.

For a family of similar tasks, a simple standard-data model might be:

where t is predicted basic time, q is quantity handled, d is a relevant distance, and β₀, β₁, and β₂ are estimated coefficients. This linear form is only appropriate when analysis supports approximate linearity over the stated validity range. It should not be extrapolated beyond the observed range without engineering justification.

Worked example 2: assembling a standard from standard data

An operation consists of four elements. The standard-data library gives the following normal times:

A 10% allowance is defined as a proportion of available working time. Thus:

The standard is 0.889 minutes per unit, or approximately 67.5 units per hour of standard time because:

This capacity interpretation assumes continuous availability for the operation and does not automatically account for staffing constraints, breaks outside the allowance model, quality losses, or machine downtime.

3.3 Statistical and managerial controls

Standard data should be tested for repeatability, reproducibility, and representativeness. Analysts should examine variation, outliers, method changes, and interactions. A value may be statistically stable yet operationally invalid if it represents a method that is no longer safe or available.

Version control is essential. A changed component, fixture, tool, or software instruction can invalidate a time value. Access should be role-based: analysts may edit, supervisors may apply, and governance personnel may approve. Audit trails should preserve the old value, the reason for change, and the effective date.

Standard data improve speed and consistency, but careless reuse creates systematic error. A value developed for a small, flexible component may not apply to a large, slippery, or fragile component even if the operation has the same name.

4. Predetermined Motion-Time Systems

A predetermined motion-time system assigns time values to standardized human motions or motion sequences. The time is determined from a published system of motion descriptions, classification rules, and time units. PMTS can be applied before a job is produced, making it particularly useful for method design, product design, line balancing, and estimating labor content.

PMTS differs from a stopwatch study in its primary source of time. A stopwatch study observes completed cycles and adjusts for performance. PMTS analyzes the defined method and assigns values to its motions. It therefore requires a precise method description and does not automatically reveal whether the method is physically safe, practical, or acceptable to workers.

4.1 General PMTS procedure

A PMTS analysis normally involves:

1. Define the task, workstation, object, and method.
2. Establish the start and end points of the operation.
3. Divide the method into recognized motions or sequence activities.
4. Determine variables such as distance, object control, precision, force, body movement, and placement condition.
5. Read the appropriate time values from the system.
6. Sum the time values and convert the system's time unit to seconds or minutes.
7. Add appropriate allowances and document assumptions.
8. Validate the result through pilot observation, ergonomic review, and comparison with related standards.

A PMTS result is often expressed as a sum:

where T_b is total basic time, tᵢ is the assigned time for motion or sequence i, and the summation covers all defined elements. If the system uses a time unit such as TMU, the conversion must be stated. In MTM conventions, one TMU is commonly defined as 0.00001 hour, which equals 0.0006 minute or 0.036 second. The analyst must verify the convention of the specific system and edition being used.

4.2 MTM

Methods-Time Measurement decomposes manual work into basic motions. Depending on the MTM variant, recognized elements include reach, move, turn, apply pressure, grasp, position, release, disengage, eye movement, and body motions. The assigned value depends on characteristics such as distance, control, object condition, precision, and force.

MTM-1 provides highly detailed analysis and is appropriate where method precision justifies the effort—for example, short-cycle manual assembly, method design, and comparison of alternative layouts. More aggregated MTM variants reduce analysis time for longer or less repetitive work. The analyst must use the correct data card or software, since the classifications and values are system-specific.

MTM is especially valuable when the analyst wants to compare methods before equipment is built. It can show that reducing reach distance, improving presentation of parts, or allowing simultaneous hand motions may reduce time. Nevertheless, the assigned time does not prove that the motion is ergonomic. A short motion repeated thousands of times may still create risk.

4.3 MOST

Maynard Operation Sequence Technique is a sequence-based PMTS approach. Instead of analyzing every basic motion separately, MOST identifies standard activity sequences. Common sequence families include general move, controlled move, tool use, equipment use, and manual or process activities. A sequence model describes the pattern of action, and index values are converted into time through the system's prescribed factor.

In a typical BasicMOST general-move sequence, the analyst considers parameters such as action distance, body motion, gain control, placement, and return. The exact syntax, index values, and variants must be taken from the licensed MOST system and training materials. It would be unsafe to reproduce a partial code table as if it were universal. MOST is generally faster than highly granular MTM for many medium- and longer-cycle operations, while MTM can provide finer motion-level discrimination.

4.4 MTM and MOST compared

Neither system is automatically superior. Selection depends on cycle length, repetition, method stability, required precision, analyst capability, data availability, and the consequences of error.

5. Selecting and Applying the Appropriate Technique

The central managerial question is not “Which system is most sophisticated?” but “Which system gives a sufficiently accurate, transparent, and economical result for this decision?”

Direct time study is often appropriate when the operation exists, is stable, and has sufficient repetition. Work sampling is useful for estimating activity proportions, especially for irregular work and delay analysis. Standard data are efficient for recurring elements. PMTS is valuable for new methods, product design, line balancing, and situations in which observed production data do not yet exist.

A practical selection framework is:

• Existing, stable, repetitive operation: direct study or validated standard data.
• Irregular work with many nonproductive states: work sampling and elemental analysis.
• New product or workstation: PMTS, simulation, ergonomic assessment, and pilot validation.
• Very short cycle with high repetition: detailed MTM or another fine-grained system.
• Medium or long sequence requiring rapid analysis: MOST or an equivalent sequence system.
• Highly automated process: machine-cycle analysis combined with human intervention analysis; PMTS alone is insufficient.

Time standards should be integrated with method engineering, not treated as an isolated payroll instrument. They can support line balancing, capacity planning, labor-cost estimation, incentive design, staffing, and continuous improvement. If used for incentives, the organization must ensure that quality, safety, learning, and teamwork are not sacrificed for speed.

6. Illustrative Case: Standardizing a Manual Kitting Cell

Background

A distribution company prepares kits containing four components for a medical-device service package. The cell uses two operators. Management observes variation in output and proposes a uniform labor standard for staffing and line balancing. The operation involves reaching into bins, selecting components, checking labels, placing components in a tray, and closing the kit.

Problem

Initial stopwatch observations range from 1.6 to 2.8 minutes per kit. Supervisors argue that the slow observations should be excluded, while employees report that bins are sometimes empty, labels are difficult to read, and the workstation becomes uncomfortable during long batches. A single average would combine method variation, delays, fatigue, and worker pace.

Analysis

The improvement team first defines the approved method and separates abnormal events from normal operating conditions. Work sampling identifies empty-bin waiting as an unavoidable but correctable delay. Ergonomic assessment identifies excessive forward reaching and visual difficulty. A standard-data review finds validated values for component retrieval and tray placement, but not for the new label-check activity.

The team uses PMTS to compare two layouts before physically rebuilding the cell. The revised layout places high-frequency components within the primary reach zone and presents labels at a consistent angle. MOST is selected for the broader sequence because the operation is longer than a simple micro-motion task and several alternative layouts must be compared quickly. MTM is used selectively to examine the critical label-positioning motion.

Approach and solution

The company:

1. establishes a documented method and replenishment trigger;
2. separates normal work from stockout delays;
3. redesigns bin locations and label presentation;
4. uses validated standard-data elements for recurring actions;
5. applies PMTS to the revised sequence;
6. conducts a pilot study with trained operators;
7. sets personal and fatigue allowances after reviewing environmental and ergonomic conditions;
8. retains a separately reported delay allowance for unavoidable replenishment activity;
9. trains supervisors not to use the standard as a demand for unsafe speed;
10. schedules a review after the first month and whenever the kit or layout changes.

Outcome

The revised method reduces reach distance and improves label visibility. Variation decreases, and the organization obtains a transparent standard that distinguishes labor content from replenishment loss. The standard supports staffing and line balancing, while the delay record directs a separate materials-management improvement. Employees accept the result more readily because they participated in method definition and can see the assumptions.

Learning points

The case demonstrates that a time standard is a socio-technical design decision. Better measurement alone cannot correct poor layout, unreliable material supply, or unsafe work. PMTS is most effective when combined with ergonomic analysis, standard-data governance, pilot validation, and employee involvement.

7. Limitations, Ethics, and Contemporary Developments

7.1 Technical limitations

All work-measurement systems depend on method definition. If the method changes, the standard may become invalid. Rating introduces judgment error in direct studies. PMTS may overlook learning, emotional effort, interruptions, cognitive complexity, or the practical effects of fatigue. Standard data may be misapplied outside their validity range. Allowance percentages may conceal variation rather than explain it.

Validation should therefore compare the resulting standard with independent observations, process capability, quality results, ergonomic indicators, and worker feedback. A standard that produces chronic overtime, unsafe postures, or quality deterioration is evidence of a defective system, even if its arithmetic is correct.

7.2 Ethical and governance issues

Standards affect workload, performance evaluation, staffing, and sometimes compensation. Ethical use requires transparency about methods, access to challenge procedures, protection against discriminatory assumptions, and respect for privacy. Individual monitoring data should be collected only for legitimate purposes, retained securely, and not converted into punitive rankings without due process.

Regulatory requirements concerning occupational safety, working time, breaks, disability accommodation, and collective bargaining take precedence over production targets. A standard cannot authorize work beyond legal or medically acceptable limits. Where a union or works council is involved, consultation and agreement may be required.

7.3 Digital tools and AI

Modern systems can store standard data in cloud databases, connect time standards to digital work instructions, and use computer vision or wearable sensors to identify motions. Machine learning can assist anomaly detection and predict time from product attributes. However, automated prediction does not eliminate the need for human validation. Sensor data may contain bias, surveillance risks, or errors caused by occlusion and unusual work methods. Explainability, consent, data minimization, cybersecurity, and auditability are essential.

A responsible digital architecture keeps the human-approved method definition, source data, model version, confidence information, and decision record together. AI should support analysis—not silently determine a worker's legitimacy, pace, or entitlement to rest.

8. Best-Practice Checklist

Before releasing a standard, the analyst should ask:

• Is the method clearly defined and currently available?
• Are observed, normal, basic, and standard times distinguished?
• Is the allowance convention explicitly stated?
• Are personal, fatigue, delay, and special allowances separately justified?
• Have ergonomic hazards been corrected rather than merely priced into time?
• Are data sources, validity ranges, and revisions traceable?
• Has the standard been validated on independent work?
• Have workers and relevant representatives been consulted?
• Are quality, safety, learning, and teamwork protected from speed pressure?
• Is the selected PMTS or standard-data method proportionate to the decision?
• Are digital tools governed for privacy, bias, and explainability?

Chapter Summary

Allowances convert normal time into a standard that recognizes legitimate personal needs, fatigue, unavoidable delays, and special conditions. The analyst must distinguish allowance conventions because S = N ÷ (1 − A) is not equivalent to S = N(1+a). Allowances should be evidence-based, transparent, separately identified where useful, and never used to justify unsafe or poorly designed work.

Standard-data systems organize validated elemental times for reuse. Their quality depends on precise element definitions, validity ranges, statistical and engineering review, version control, and periodic validation. PMTS predicts time from a defined method by assigning values to motions or sequences. MTM provides detailed motion analysis, while MOST uses more aggregated activity sequences and can support faster analysis. Both require trained analysts, correct system data, ergonomic review, and operational validation.

The professional purpose of work measurement is not simply to accelerate workers. It is to design feasible methods, support capacity and staffing decisions, reveal process losses, and establish fair and technically defensible expectations. Effective practice integrates measurement with ergonomics, quality, employee participation, governance, and continuous improvement.

Key Terms

Allowance: Time added to normal time for legitimate personal, fatigue, delay, or special conditions.

Basic time: Time for the defined work content before allowances are added.

Delay allowance: Time recognizing unavoidable interruptions outside the worker’s control.

Fatigue allowance: Time recognizing recovery from physical, environmental, or mental demands.

Normal time: Observed time adjusted by a performance rating.

Observed time: Time directly recorded during a work measurement study.

Performance rating: Judgment of observed pace relative to a defined normal pace.

Personal allowance: Time for essential personal needs.

PMTS: Predetermined motion-time system assigning time values to defined motions or sequences.

Standard data: Validated time values for recurring elements or conditions.

Standard time: Time allowed for a qualified worker to complete a defined task using an approved method, including allowances.

Special allowance: Time for specific activities or conditions not covered by general allowances.

MTM: Methods-Time Measurement, a detailed motion-based PMTS.

MOST: Maynard Operation Sequence Technique, a sequence-based PMTS.

TMU: Time Measurement Unit used in some PMTS; in MTM convention, commonly 0.036 second.

Work sampling: Statistical observation of activities to estimate proportions of time in defined states.

Method definition: Precise specification of how a task is to be performed.

Version control: Governance of changes to data, methods, and approved standards.

Review Questions

Short Answer Questions

1. What is the difference between normal time and standard time?
2. Why must an organization distinguish additive allowances from allowances defined as a proportion of available time?
3. Give two examples of special allowances.
4. What information should accompany a standard-data time value?
5. How does PMTS differ from a conventional stopwatch study?

Long Answer Questions

1. Explain the purposes and appropriate uses of personal, fatigue, delay, and special allowances.
2. Describe the stages involved in developing and governing a standard-data system.
3. Compare MTM and MOST in terms of analysis unit, detail, speed, and suitable applications.
4. Discuss why ergonomic assessment must accompany the development of time standards.
5. Explain the ethical and governance risks of using digital monitoring and AI in work measurement.

Analytical / Application Questions

1. An operation has an average observed time of 3.20 minutes and a rating of 105%. Personal, fatigue, and delay allowances are 5%, 6%, and 4%, respectively, defined as proportions of available time. Calculate normal time and standard time, and state the assumptions behind your calculation.
2. A company wants to apply a standard-data value for “retrieve component” to a new product that is twice as large and must be handled with gloves. Identify the validity questions that should be answered before reuse and recommend a validation approach.
3. A new assembly cell has not yet been built, but management needs labor-content estimates for two layouts. Recommend whether direct study, standard data, MTM, MOST, or a combination should be used. Justify the choice and identify the risks of relying on PMTS alone.

Multiple Choice Questions with Answers

Question 1

Which expression represents normal time when observed time is adjusted by a decimal performance rating?

A. N = Ō ÷ R

B. N = Ō × R

C. N = Ō + R

D. N = R ÷ Ō

Correct Answer: B. N = Ō × R

Question 2

If normal time is 4 minutes and the total allowance is 20% of available working time, what is the standard time?

A. 4.20 minutes

B. 4.80 minutes

C. 5.00 minutes

D. 5.20 minutes

Correct Answer: C. 5.00 minutes

Question 3

Which allowance recognizes essential activities such as obtaining water or using restroom facilities?

A. Personal allowance

B. Delay allowance

C. Special allowance

D. Setup allowance

Correct Answer: A. Personal allowance

Question 4

Which is the best reason to maintain validity ranges in a standard-data system?

A. To ensure every job receives the same time regardless of conditions

B. To prevent values from being applied outside the conditions for which they were established

C. To eliminate the need for method definitions

D. To replace ergonomic assessment

Correct Answer: B. To prevent values from being applied outside the conditions for which they were established

Question 5

What is the primary analytical distinction between MTM and MOST?

A. MTM uses machine time, whereas MOST uses labor cost

B. MTM analyzes basic motions, whereas MOST analyzes standard activity sequences

C. MTM is observational, whereas MOST is purely statistical

D. MTM includes allowances, whereas MOST prohibits them

Correct Answer: B. MTM analyzes basic motions, whereas MOST analyzes standard activity sequences

Question 6

In the stated MTM convention, one TMU is equal to:

A. 0.0036 second

B. 0.036 second

C. 0.36 second

D. 3.6 seconds

Correct Answer: B. 0.036 second

Question 7

Which situation is most suitable for using work sampling?

A. Estimating proportions of time spent waiting, working, and other defined states in irregular work

B. Assigning a precise value to every finger motion in a short assembly

C. Determining the legal minimum wage

D. Replacing all ergonomic assessments

Correct Answer: A. Estimating proportions of time spent waiting, working, and other defined states in irregular work

Question 8

A delay caused by chronic equipment breakdowns should generally be:

A. Automatically hidden in the personal allowance

B. Treated as a permanent fatigue allowance

C. Investigated as a process loss rather than automatically embedded in the standard

D. Removed from all records

Correct Answer: C. Investigated as a process loss rather than automatically embedded in the standard

Question 9

Which practice best supports ethical use of time standards?

A. Changing standards without recording the reason

B. Using standards to require unsafe speed

C. Providing transparency, challenge procedures, and protection of safety and quality

D. Monitoring workers indefinitely without governance

Correct Answer: C. Providing transparency, challenge procedures, and protection of safety and quality

Question 10

An operation has a normal time of 2.40 minutes and an additive allowance of 15%. What is the standard time under the additive convention?

A. 2.04 minutes

B. 2.55 minutes

C. 2.82 minutes

D. 3.15 minutes

Correct Answer: B. 2.55 minutes