A time study is a structured work measurement technique designed to determine the time required for a qualified worker to complete a specific task at a defined level of performance. This industrial engineering tool involves direct observation and precise timing of work elements to establish a consistent labor standard. The resulting standard time provides a reliable metric for various operational functions, including efficiency measurement, production planning, and labor cost estimation. Developing an accurate standard time requires a careful, multi-step process.
Essential Pre-Study Preparation
Before any timing begins, the scope and conditions of the study must be clearly defined. Preparation starts with identifying the precise objective, such as measuring the time for a specific assembly operation or material handling process. Defining the task clearly prevents scope creep and ensures the resulting standard applies only to the intended work.
Selecting the right person to observe is important, as the study results will be applied across the entire workforce. The chosen worker should be well-trained, demonstrate an average level of skill, and consistently perform the task using the documented method. Observing an exceptionally fast or slow worker will skew the data and lead to an inaccurate standard.
The analyst must gather the necessary equipment, which typically includes a reliable stopwatch and detailed observation forms. Preparation involves communicating the study’s purpose to the worker and their supervisor. This transparency minimizes apprehension and encourages cooperation, ensuring a representative performance is observed.
Standardizing the Work Method
A time study measures a defined method, not just the speed of an individual. Therefore, the task must first be broken down into discrete, measurable elements, each with clear start and stop points. This elemental breakdown allows the analyst to isolate parts of the work cycle for separate analysis and rating.
Consistency in the work process is paramount; the exact sequence of motions, tools, and equipment must be documented and standardized. If the current method contains obvious inefficiencies, improvements should be implemented and stabilized before the study proceeds. Timing a flawed method creates a standard that perpetuates wasted effort.
Observing and Timing the Task
The actual timing phase involves collecting raw data by observing multiple cycles of the standardized task. An analyst typically uses one of two primary stopwatch techniques: the continuous method or the snapback method.
Continuous Method
In the continuous method, the stopwatch runs without interruption for the entire study, recording all delays and interruptions. The time for each individual element is calculated later by subtracting the preceding element’s recorded time from the current one.
Snapback Method
The snapback method involves resetting the stopwatch to zero at the end of each elemental observation. This allows the analyst to directly read the elapsed time without subsequent subtraction. However, the snapback method introduces a small, unrecorded time gap due to the physical action of resetting the watch.
To ensure statistical relevance, the analyst must determine the number of cycles to observe, sufficient to capture the normal variation in element times. During timing, the analyst records any foreign elements—unexpected interruptions external to the primary process. These are recorded separately so they can be excluded from the elemental time calculation.
Adjusting Time with Performance Rating
Raw observed time reflects only the pace of the specific worker, making it insufficient for setting a labor standard. Performance rating, or leveling, adjusts the observed time to what a qualified worker achieves at a “standard pace.” The standard pace is defined as 100% and represents the speed a trained worker can maintain over an entire shift.
The analyst compares the observed worker’s pace against this standard pace and assigns a rating factor, expressed as a percentage. If the worker is faster, the rating is above 100%; if slower, it is below 100%. This process requires the analyst to maintain objectivity and relies on consistent training to accurately evaluate the worker’s speed.
One recognized approach is the Westinghouse system of rating, which assesses the worker based on four factors: skill, effort, conditions, and consistency. The rating factor is multiplied by the average observed time to yield the Normal Time (NT). Normal Time is the time required to perform the task at the defined standard pace, neutralizing the influence of the individual worker’s unique speed.
Calculating Standard Time with Allowances
Normal Time represents the time required to complete the task with no interruptions, which is unrealistic for a full workday. Standard Time is created by increasing Normal Time with allowances, accounting for necessary breaks and delays. These allowances compensate the worker for factors beyond their control and for legitimate personal needs.
Allowances are generally categorized into three types: personal, fatigue, and delay (PFD). Personal allowances account for needs such as restroom breaks, often set at a constant rate. Fatigue allowances provide time for the worker to recover from physical or mental exertion, varying based on the work environment and physical effort required.
Delay allowances account for unavoidable interruptions not part of the standard cycle, such as waiting for materials or minor equipment adjustments. The final Standard Time is calculated using the formula: Standard Time = Normal Time $\times$ (1 + Allowance Factor). This calculation establishes a fair and attainable time standard that allows for human factors while maintaining productivity expectations.
Applying Time Study Results for Efficiency
The resulting Standard Time is a powerful metric that serves as the foundation for optimizing business operations. It is used to establish fair production goals, allowing management to create accurate schedules and determine expected output levels. Companies rely on these standards to calculate labor costs per unit, which informs product pricing and budgeting decisions.
The standard time also provides a baseline for continuous improvement efforts by highlighting methods that fall significantly above or below the expected time. The data aids in determining appropriate staffing levels, ensuring the workforce is correctly sized to meet demand. By providing a consistent, measurable expectation, time study results allow organizations to manage capacity and measure performance.