The pace judgment is a subjective assessment of the relative rate of work observed. The analyst compares the observed operator’s performance with a concept of normality. Applied to the observed time, one gets the Normal time. It is interpreted in the following way:
- Pace > factor 100%: The observed cadence is faster than the standard.
- Pace < factor 100%: The observed cadence is slower than the standard.
The ” normal ” worker
An average worker is the person who possesses the intelligence and physical aptitude required to perform a task according to satisfactory standards of quantity, and whose skill and performance is the average level.
It is always complex to judge a ” normal ” pace. Some useful tips will be used to judge effectively:
- Do not judge extreme gaits. It is possible to have an accuracy of about 5% for gaits ranging from 70 to 130%
- Ensure that the work judged is carried out under standard conditions: trained and accustomed personnel, usual tools…
- Take into account the manipulated objects and the parts of the body used. A flexible movement cannot be judged in the same way between a carpenter and a television fitter.
- For specific operations such as control, seek advice from staff who master the subject.
- Validate in a group the choice of the person to ” Judge “. That person has to make a consensus.
- To be relevant, the analyst must be well aware of the work to be done.
The performance ratio
It is also known as the speed ratio or the ratio of effort and skill. The ratio is identified through 8 questions:
- Is it possible to give a universal mathematical value at the speed of the operator? : Usually the answer is ” Yes “, because there is always a reasonable relationship between the different activities.
- Is it possible to determine it only by a judgement? : If you answer no, this method does not apply. However, although the method is not infallible, the answer is always ” Yes “.
- If this is possible, is it applicable to all types of manual work? : The challenge is to ensure that the method can be applied to the entire study.
- Is it possible to do this for all speeds? : It is indeed more difficult to make a judgement when the speeds vary strongly. Thus, it is necessary to ensure that the variability in the measurements is less than 50%1.
- Can everyone make this ratio? : The challenge is to see if training is necessary to make the judgement to ensure the quality of the measure.
- Is this method repeatable with all observers? : In the continuation of the previous question, certain quality of rhythm judgement may be necessary. Depending on the people and with regard to the operations to be judged, the rhythm can be judged different and thus distorted the measures.
- Is it dependant on the operators? : When more than one operator can be taken to carry out the study, it is necessary to choose the one that is most receptive to time analyses. Beyond that it is necessary to take the one that corresponds most to the average.
- Can we train and make him learn? : Finally, the question is whether the method of work judged can be transposable to all, while having reasonable variability.
The Westinghouse system
The Westinghouse System was published in 1927 by Lowry, Maynard and Stegemerten in Westinghouse Electric Corporation. Also called the LMS system, named after its creators, it proposes to judge the allure according to 4 factors, and gives for each a scale of value depending on the performance. Source: B. Niebel, A. Freivalds (1999)-Methods, standards and Work Design
Competency defines a person’s ability to master a specific method. It depends on the training and the seniority, and indicates the level of coordination between the mind and the movements. In the Westinghouse system, the different categories are defined in this way:
- Low skill: can not coordinate mind and hands, movements are awkward, task sequence is uncertain, untrained at work, hesitation, inappropriate movements, errors appear frequently, lack of confidence, not able to take initiatives.
- Medium Skill: safe behavior, little seeming a little slow in movements, control of work, no hesitation in the sequence of operations, good hand coordination, work with precision, satisfactory work.
- Good skill: Self-confident, natural aptitude at work, well trained, work well without control of actions, work without errors in the sequence, uses all the assets of the material, works fast while guaranteeing the quality, the performance is good while Quiet, work in rhythm and coordination.
- Excellent skill: naturally made for the job, seems super trained, the movements are so fast and fluid that we can not follow them, work as a ” machine “, the tasks follow without hesitation and reflection.
The efforts represent the vivacity at work. This is how the operator uses his energy at work. In the same way, there are different levels to evaluate the efforts. Here is the description of the category ” Good effort “:
- Work in Rhythm
- Downtime is minor or non-existent
- Works conscientiously
- Works at a good pace and allows to be maintained throughout the day
- The tasks are done with conviction
- Gladly accepts the advice and solutions
- Offers improvement solutions
- Keeping your Position tidy
- Use the appropriate tools
- Keeps its tools in order
This system of measurement highlights the fact that working conditions can have a strong influence on the quality and performance of the work. We are talking about visual, sound, odor, or thermal conditions.
In this system, the variability in the working time is an indicator of allure. Thus, if there is no variability in the operating times, this factor is considered to be perfect.
The Synthetic method
Developed in the years 19502, this method proposes to compare a real measure of working time with respect to a predetermined measure. The pace factor in this case is therefore equal to:
Pace factor = predetermined time value of the operation/average of current times
The Objective method
The objective ratio is a method developed in the years 1950-19603. This method assumes that the judgement of allure must be as objective as possible. The creators have ruled that the allure is a function of the skill, the aptitude and the effort of the operator.
Step 1: The standard ratio
The first step is to define the ratio of the observed rhythm compared to a standard rhythm. For this, we will follow the following steps:
- Identify the standard time. To do this, we start from a rule which is to say that the standard time is 130% of the time measured under the following conditions: an operator with the necessary skills, in good physical condition and working at a pace that is known to maintain day After the day.
- Define a physical representation of the previous standard time. To do this, you have to make different videos of the same operation at different paces. With the teams, one chooses then the sequence, which seems for everyone the normal appearance. This video represents a 100% allure.
Step 2: Apply an experimental increase
Not all tasks can be done at the same rate. This depends on a number of important factors that are met under the term ” difficulty adjustment “. This increase is based on 6 parameters and according to the table below:
- number of members used: making a movement of the fingers and arm takes about 8% more time than moving only the forearm and fingers5. Thus, the table shows percentages to be added depending on the type of movement.
- Foot Pedal: Using the feet also influences the cycle time as well as using the hands and therefore a percentage must be allocated6.
- using the 2 hands: using both hands does not amount to working twice as fast. Studies show that in general, performance increases by 18%7.
- Hand/eye Coordination: affecting the movements as positioning or grasping, at the most coordination is necessary, at the most the cycle time is long.
- handling Required: the number and type of Handling influences the cycle time.
- Weight: studies show that there is a linear relationship between cycle time and weight, for weights ranging from 4kg to 18kg8. On the other hand, below 4kg, the cycle time decreases more and more the weight is low.
The physiological ratio
The principle of this method is based on the measurement of the actual energy of the body expended to perform a task. For this, we can measure different indicators:
- Heart Beats
- Oxygen consumption
- Energy consumption
Other pace judging Systems
In addition to the above systems, there are many others but have not met with success.
The Hummel ratio
Developed by Professor Hummel, this ratio takes into account the ” Tempo ” and ” efficiency ” at work. The tempo is identified as a percentage compared to a normal rate (100%). Efficiency is judged according to the following scale of value:
- Superior (+ 0.15): the operator works with the whole body and with smooth and perfectly coordinated movements.
- Excellent (+ 0.1): the operator works with a high degree of flexibility and coordination.
- Good (+ 0.05): the operator works relatively flexibly, without too much imbalance and hesitations are present occasionally.
- Medium (0): the operator has no particular hesitation or coordination problem.
- Fair (-0.1): There are unbalanced movements that are indicative of a coordination problem. Hesitations are also present.
- mediocre (-0.2): There are frequent hesitations and movements of hands, feet… are poorly coordinated.
The use of this ratio requires that the ” Tempo ” be multiplied by ” efficiency “. For example, for a tempo of 1.2 with a higher efficiency, this gives 1.2 * 1.15 = 1.38. The operator in this case works at 38% above the performance judged normal.
The ratio of Shumard
In the years 40, F. W. Shumard developed an evaluation system based solely on the judgement of Speed9. The measurement scale proposes to perform a time-judged/normal-time ratio. The normal speed of 60 corresponding to a speed carried out under standardized conditions, without premiums or other benefits in relation to productivity and being considered in the ” average ” of the enterprise.
1 – B. W. Niebel (1955) – Motion and Time study
2 – R. L. Morrow (1957) – Motion Economy and work measurement
3 – Mr. E. Mundell (1960) – Motion and Time Study: Principles and practices
4 – Mr. E. Mundell (1948) – An evaluation of performance rating
5 – Mr. E. Mundell (1949) – Unpublished research
6 – R. M. Barnes, H. Hardaway, O. Podolsky (1942) – Which pedal is best
7 – E. Ischinger (1950) – An analysis of some differences between one and two handed industrial work
8 – R. B. Solberg (1946) – Time allowances for handling of weights for use in stopwatch time studies
9-F. W. Shumard (1940) – A Primer Time Study
K. C. Arora (2004) – Production and operations management
L. Brouha (1960)-Physiology in industry