What is Design of Experiments (DOE)?
Design of Experiments is a useful tool in Lean Six Sigma. It is a statistical hypothesis testing tool that systematically determines the relationship between factors affecting a process and the output of that process. In other words, it is used to find cause-and-effect relationships. A well-designed experiment allows us to isolate the impact of each X and to find the combination of X’s that yields the best outcome.
Let’s Take a Look at Marit’s Example
While staying in with her parents to minimize potential spread and/or exposure to COVID-19, she was working on completing her Applied Statistics course requirements and also on keeping her parents active and occupied while in the house. She decided why not combine the two together.
Beginning the Experiment
The objective of her experiment would be:
- To keep her Mom, who has Alzheimer’s, mentally engaged and physically active during the stay at home order
- Determine the most effective walking method for her mom.
She chose to focus on the relationship between her Mom’s step count and walking time and 3 input factors (footwear, direction walked, and carrying weights).
For the experiment, she established a designated walking route down the hall of the house which included a designated standard start/finish line spot that was taped to the floor in the kitchen and the edge of carpeted bedroom at end of hall as the designated start/finish line.
Her mom did the walking on each trial. Marit recorded the step count and times for each walk using the stopwatch function on her iPhone. They conducted several practice runs to ensure she could execute the trials with minimal reinstruction between trials and she could consistently use the iPhone stopwatch function. With the experiment designed, they conducted the experiment and gather the data.
What Were the Results?
Footwear and Walking Direction were the only two significant factors. Her walking was optimized when she was wearing shoes and walking towards the kitchen. And even though Marit chose this experiment with the ulterior motive of keeping her mom active (she ended up walking over a mile for the experiment), she also found that this type of experiment and data could be useful in the real world.
- For caregivers of individuals with Alzheimer’s
- The effectiveness of having very visual “standards” available to minimize confusion and minimize the need to repeat instructions for repetitive tasks
- The impact of visual distractions on a person with Alzheimer’s ability to perform a task.
- Walking from the kitchen to the bedroom, her mom would one only see the hall walls and an opening into bedroom
- Walking from the bedroom to the kitchen, her mom would see a shelf and an island with many items on them
What a wonderful example of optimizing your circumstances highlighting the use of Design of Experiments (DOE)! Great job Marit!