Time Study
Time Study is the direct observation of a task as it is performed at the job site by a trained time study analyst.
1. Time study is appropriate for manual work that can be physically observed by an analyst.
2. Time study is appropriate for repetitive tasks that can usually be done in 15 minutes or less.
3. Time study is appropriate for tasks that are repeated in a cyclical pattern over an extended period of time.
4. Time study is the most versatile and the most widely used work measurement technique.
Example of a Time Study Record
Definitions
Time Study Record: A data collection form that contains all the necessary information that is required to compute how long it should take to perform a specific task. An example of a Time Study Record form appears above and an example may also be downloaded below.
Column Number: Refers to the number at the top of each column on the Time Study Record form.
Sample Size: The minimum number of observations required to achieve a statistically accurate result. The equations for computing the minimum sample size will be discussed in a future module assignment. In order to observe enough total cycles the analyst may conduct Time Studies on several different days in order to increase the chance of capturing any unusual events that may occur. Each future Time Study should be recorded on a new Time Study Record.
Element Description: A brief description of one small step in the entire job sequence as performed by the employee. This brief element description is shown in the column on the left side of the Time Study Record form.
Element Times (Columns 1 to 10): The actual Stop Watch Time that corresponds to how long it took the employee to execute one repetition of that element. The time to make the first part is recorded in column 1. The time to make the second part is recorded in column 2. And so on. If more than 10 parts are observed then the time for part number 11 is recorded on the Time Study Record directly below the time for the first part.
Total Time (Column 11): The sum of all the individual times for one element in the entire job sequence.
Number (Column 12): The actual number of observations for that element that were observed by the time study analyst during a single time study and that have not been circled due to unusual work conditions called foreign elements.
Foreign Element: A brief description of any foreign elements is shown at the bottom of the form in the center. A detailed discussion of foreign elements appears later in this module assignment.
Average Time (Column 13 = Column 11 divided by Column 12): The simple arithmetic average of all the recorded times for an element (the mathematical mean).
Rating Factor (Column 14): The evaluation of an employee’s actual performance in relationship to the analyst’s impression of what the normal, average speed for doing the job should be. The rating factor is recorded on the time study form as the job is being observed. Performance rating has already been discussed in a previous module assignment.
Base Time (Column 15 = Column 13 multiplied by Column 14)): The average time for an element multiplied by that element’s performance rating factor.
Frequency (Column 16): The frequency is based on the unit of measure for the job. Frequency refers to how often that element should happen, on the average, when compared to the other elements in the Time Study.
Normal Time (Column 17 = Column 15 multiplied by Column 16)): The base time for an element adjusted by the appropriate frequency for that element.
Personal, Fatigue, and Delay (P,F, and D) (Bottom of Time Study Record Form): The additional time required during the course of a normal work day for the employee to attend to their normal personal needs (personal time), and the normal decrease in productivity due to the passage of time (fatigue time), and the minor interruptions in a person’s normal work duties due to a variety of different factors (delay time). The procedure for calculating P,F, and D allowances will be discussed in a future module assignment.
Total Standard Time (Bottom of Time Study Record Form = Sum of Column 17 plus the P,F, and D Allowance): The sum of all the normal times for all the elements plus the appropriate P,F, and D allowances for that job. The total standard time is how long it should take the average, trained employee working at a normal pace and with normal effort to perform the task using the standard method.
Time Study Equipment
1. Stopwatch calibrated in 1/1000 of a minute, or in seconds.
2. Time Study Record forms.
3. Clipboard, pencil, and tape measure.
4. When appropriate, a tachometer or other gauge for determining machine speeds, feed rates, or other critical machine parameters.
Snap-Back Time Study
The stopwatch is started at the beginning of the first element in the study. At the end of each individual element, the stopwatch is read and snapped back to zero. The actual elapsed time for that one element is then recorded on the time study form. The most common problem with this technique is snapping the watch either too soon or too late for individual elements. The total time will still be accurate but the average times for the individual elements will be incorrect. At the end of the study, the total elapsed time is read from the watch and it is recorded at the bottom of the Time Study Record form.
General Time Study Procedure
1. Pick a job to time study based on any of the following:
a. Employee request.
b. Supervisor request.
c. Management request.
d. Part of a larger project.
e. Time for a routine audit.
f. Searching for any area of potential improvement.
2. Discuss the job with the section supervisor. Have the supervisor suggest a person to observe. Introduce yourself to the employee or have the supervisor introduce you. Explain the reason for the study. Try to get the employee to perform the work as he or she normally would.
3. Verify the employee is following the standard method.
4. Record the generic data about the job (type of equipment, speeds, tools, materials, etc.).
5. If appropriate, draw a simple sketch of the work area on the back of the Time Study Record form.
6. Observe the job and divide it into logical elements.
7. Watch the employee perform the job and record the actual time taken by the employee for each element.
8. Rate each element individually.
9. Continue to collect data on the operation for several complete cycles of the job.
10. Compute the base time to do each element of the job.
11. Compute the normal time for each element based on the frequency of that element in relationship to the appropriate unit of measure for the job.
12. Add the appropriate allowances and compute the total standard time to do the job.
Based on the results of a single Time Study compute the following:
1. Determine the total number of cycles to observe based on the desired confidence level.
2. Continue timing the job until enough cycles have been observed.
3. Based on the results of all the Time Studies compute the engineered standard time to perform the job.
4. Compute each employee’s productivity from each Time Study based on the new engineered standard time.
5. Have the new standard time approved and publish it.
6. Put all supporting Time Study materials in a historical file for future reference.
How to Collect Time Study Data
1. Hold your pencil in your writing hand.
2. Hold your stopwatch in your other hand.
3. Place your clipboard and Time Study Record form between your stopwatch and your elbow.
4. Stand slightly to the side and to the rear of the employee so you can observe the employee over your stopwatch.
5. Watch the employee perform the task.
6. Look at the watch and record the time on the time study form.
7. Long elements can be timed by themselves one at a time.
8. Short elements can be timed in groups (3, 4, or more at a time).
9. Foreign elements should be coded and computed at the end of the study.
Time Studies are usually done at the job site where the operation is currently being performed. Occasionally, the operation may be filmed and then the Time Study is conducted on the film of the operation. This procedure is common in learning environments but it is not common in actual practice.
Factors that Influence the Accuracy of the Standard Time
1. The efficiency of the employee being observed in relation to the analyst’s ability to correctly rate that level of performance.
2. The conditions under which the study is made:
a. How the equipment is doing.
b. Raw material quality.
c. Fatigue of the employee.
3. The way the job is divided into elements.
4. The number of cycles observed.
Foreign Elements
A foreign element is a unusual element that occurs during a normal work element.
When observed, foreign elements are noted with a code letter beside or above or below the time value, and the code letter is explained elsewhere on the time study form.
Examples of some common foreign elements:
F = A fumble which lengthens the normal work cycle.
P = A personal movement, such as scratching the ear.
M = A minor adjustment to the machine or equipment.
R = A repair or rework.
S = Replenishing supplies.
… = Any other irregular work element.
The above are only examples. The time study analyst may select any letter to represent any foreign element.
Computing Foreign Elements
1. Note the unusual element on the time study form.
2. Compute the average time for the other cycles of that element with the unusual element omitted.
3. If appropriate, deduct the average element time from the foreign element time to yield the additional time required for the foreign element. This would be appropriate if the foreign element occurred during a regular work cycle and the foreign element time also included a regular work cycle time. However, if the foreign element time does not include the time for a normal work element then use the time as originally observed.
4. Multiply by the rating factor to yield the base time for the foreign element.
5. Determine the frequency of occurrence for the foreign element and adjust by that frequency to yield the normal time per cycle.
Reasons for Omitting an Element
You must have a reason to omit an element as a foreign element. Some common reasons for omitting a foreign element are as follows:
1. The element is paid for in another part of the standard (such as personal time).
2. The foreign element does not belong in the standard (such as machine down time).
3. The time is outside the normal range of times for the element (too high or too low) and the analyst could not determine why at the time of the study (analyst error).
Circle element times that are to be omitted from inclusion in the standard time, or that are to be treated uniquely in the calculation of the standard time.
Do not circle an element just because it is unusually large or small in comparison to other times.