### How well does the improved process fulfill customer

Workshop: Histograms and Descriptive Statistics

The tools practiced in this workshop are:
• Histograms
• Descriptive statistics

Situation:
Consider that you/your group works for a housekeeping company, and you have been tasked with collecting data to document the current status of your cleaning performance. This data is needed to establish a baseline measurement at the beginning of your Lean Six Sigma project so that you will have a measurement to compare against later once the process has been improved.
Please note that the customer specifications for your cleaning service process are:
Target: 30 ± 5 minutes (lower specification limit: 25 min and upper specification limit: 35 min)

Instructions:
Use information from your training manual in Measure Phase - Lessons 9-11 to assist you with the activities that follow. Be sure to follow the "best practices" for each tool you use in this workshop.

Your baseline data of cleaning times is provided. Use Microsoft Excel to calculate your descriptive statistics and create a histogram of your data.

Activities: (also see next page)
1. For the cleaning times documented by your cleaning process, what is the:
a. Average cleaning time in minutes?
b. Standard deviation in minutes?
c. Range in minutes?
2. Create a histogram that summarizes your data set (i.e., measurements of the cleaning times in minutes) Your histogram should have at least 10 bars:
[Create your histogram on the Workshop Data Sheet "Cleaning Time Data" and submit the Excel spreadsheet with your workshop.]
3. Near the end of your Lean Six Sigma project, after you have implemented solutions to improve your cleaning process, you measure the process performance again and get the following results:

Cleaning time - Average: 30 minutes; standard deviation: 15 minutes cm; range: 10-75 min

a. Have you improved the process? Yes or no and why.
Hint: Perform a before and after comparison by comparing the baseline measurements in Activity #1a-c of this Workshop with the measurements given in this question.

b. How well does the improved process fulfill customer requirements?
Hint: Perform another comparison by comparing the measurements given in this question to the customer specifications given in the "Situation" part of this Workshop.

4. Use QI Macros to create a Histogram for the data in the "Help Desk Time" tab in the Workshop Data Sheet.