Time Studies

Skill level: Basic

Description

The main objective of a conducting a time study is to visualize and understand the effect of time in the behavior of a process. This approach involves collecting data using a sampling method correlating time and date with events.

Benefits

  • Creates a clear understanding of the time effect
  • Provides the necessary data for continuous improvement
  • Using time series chart, provides the visual representation that can explain trends, seasonality, and time variation

How to Use

  • Step 1.  Identify the process to be studied and all the key factors.
  • Step 2.  Develop a detailed data collection plan and communicate it to all stakeholders.
  • Step 3.  Create data collection form/method; validate and collect data.
  • Step 4.  Analyze data with the proper time series chart for the data.
  • Step 5.  Make proper deductions and conclusions, identifying opportunities for improvement where applicable.

Relevant Definitions

Key factors:  Elements of a process that affect the outcome, such as time of day and shipping method.

Example

A project leader seeks to reduce lead time in parts delivery from the time the provider has ordered the parts to the time they are delivered on site to service grounded commercial airplanes. The key (high level) factors are:

  • Time of the day (hour) order is placed
  • Day of the week order is placed
  • Number of different parts ordered
  • Parts type: engine, landing gear, mechanical control, electronic control
  • Shipping date and time
  • Shipping method
  • Lead time to shipping and receiving, calculated from the dates

Once the data are collected (see table below), a time series chart can be created to visualize the lead time for each one of these transactions.

Tool_Time_Studies_Table1

The chart below shows that some lead times are fairly short and within customer expectations, but a certain number are much longer. More data might be needed to understand the issues.

It is beyond the purpose of this tool to discuss or explain how these data should be analyzed to define where the focus should be for future improvement.

Tool_Time_Studies_Figure1

 

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