What do all the lines and boxes mean on a boxplot?

The Boxplot is one of simplest graphical tools to look at, and a tool I use very frequently when first reviewing my data sets. It is a great visual tool for showing the variation and average of a data set, that is not sensitive to outliers (nonparametric approach). The chart shows how the data breaks down by categories, to help you identify areas of concern or potential causes of your problem.

However, it is the most confusing chart to explain how each piece of the box is calculated. When teaching a basic statistics class, I actually avoid discussing the boxplot, because it brings about many questions and becomes a distraction for the class attendees.

When we look at the boxplot simplistically, it gives us a quick understanding of our data. Let's look at an example from Minitab.

You should be able to draw some simple conclusions from the chart

• The boxplot for the paint data shows that paint blend 4 has both the highest median and least variability, with an interquartile range of only 3.10.
• Blends 1 and 3 appear to have roughly similar medians and variability.
• Blend 2 has the lowest median and greatest variability, with an interquartile range of 11.72. The short whiskers indicate clumps of data near the box endpoints.
• There are no outliers in the data

Ultimately, the very next question is always "how are the box and lines calculated?"

Let's breakdown the chart to help clarify it.

1. Determine Median (50th percentile) = 146
2. Determine 1st quartile (25th percentile) = 141.5
3. Determine 3rd quartile (75th percentile) = 150
4. Calculate outlier range “whiskers” as (1.5 * (Q3-Q1)) = 12.75 from median (133.25 to 158.75)
5. Calculate Interquartile Range (IQR) by taking Q3 – Q1 = 150 – 141.5 = 8.5
6. Draw line through median
7. Add asterisks if data outside outlier range

You can also download the Boxplot guide below for future reference.

Hopefully this helps you understand box plots, and you see the need to use them prior to analyzing
any data set.

8 ways why batching is bad for your business

One of the most common questions we get when reviewing a process:

"What's wrong with batching? I can produce so many more widgets when I do it this way?"

When I first started out in Lean, I had the same questions. It seems more efficient to the worker, and therefore it doesn't make sense to them that someone would want to change that. It took a few improvements before things started to sink in for me.

Just so everyone is on the same page, when you batch, you don't complete tasks one item at a time, you wait until you have a few items, then complete the task all at once. Usually this is because the time to get setup to complete the task takes a while, so it's more efficient to do the task all at once. However, the time waiting for a large enough batch to complete causes the next step to wait, then it generates a large amount of inventory all at once, which is unable to deal with the inventory and therefore it will need to be stored or will sit waiting to be worked on.

Don't believe us? Check out this video of envelope stuffing, and you'll understand why one at a time is better.


Here are a list of reasons why batching and inventory is bad:

1) Delays in detecting problems - The parts are not allowed to move to the next process until the whole batch is complete, so any problems found later in the process are delayed, adding to the number of items with problems that will need to be reworked or thrown away, increasing costs.
2) Taking up resources - Any items being produced that are not needed right now are taking up time at that process step, that could be better spent on things that are needed, which delays deliveries to customers.
3) Inventory cost - The labor and cost to process the items has been spent, but since it's not needed yet, it will take longer to get paid by the customer, which reduces cash flow and the cost of capital (money that could be getting a return on investment).
4) Cost to store inventory - Inventory needs to be stored, so there is a cost to process and record it, package it to protect it from damage, put it somewhere out of the way (requiring more floor space, which adds to the cost of utilities for lighting, heating and cooling).
5) Potential for problems - Once the inventory is stored, there is an increased chance that it gets damaged, deteriorates, corrodes, etc. This requires it to be redone or reworked or discarded, which costs money.
6) Loss of customers - If a customer cancels the order, or asks for a different version, or the part is no longer made available for sale, then the inventory becomes worthless, so the expense of buying and purchasing the items is lost.
7) Cost to dispose - There may be additional costs to deal with the scrap or unneeded items beyond the wasted labor and material costs, such as landfill disposal costs, cost to transport or pickup the items, fill out paperwork, or even properly recycle it.
8) Perception differs from reality - As seen in the video, the perception of batching may not actually result in faster processing.

Don't get me wrong, there are situations where batching is a better option in the short term (large setup times, low cost of inventory, inconsistent deliveries, etc). There are other situations, especially when ordering from a supplier, where travel and bulk discounts come into play. For these situations, an economic order quantity can be calculated that considers all these extra costs, to decide how large the batch size could be. However, in general the goal is to minimize the size of batches as much as possible by making the setup times less.

What examples do you have that helped you understand inventory and one piece flow? What other problems does inventory and batching create?

8 steps for passing the ASQ Six Sigma Green Belt or Black Belt exam

We have taught many students how to prepare for ASQ exams. I've even taken (and passed) the Certified Quality Engineer (CQE) exam once, and the ASQ Black Belt exam twice (do not let your certification expire, or you will need to re-take the exam!).

We often get asked what the best approach for passing the exam should be.

I'm going to assume that you have some prior Six Sigma or statistics training, and you are looking for a way to refresh yourself on the topics.

Since many people are now taking the Certified Six Sigma Green Belt (CSSGB) exam, I will focus a little more on that exam, but many of the tips apply to the Black Belt (CSSBB) exam.

If you have not taken any Six Sigma training, I would recommend checking out our webpage on getting free online Green Belt training

1) Order the Certified Six Sigma Green Belt Primer (QCI) and Solution Text - This will provide you with almost everything you need to know to pass the test. If you know the material in this book, there is a really good chance you will pass. You don't have to sign up for the exam yet, we will discuss that later on...


2) Read every word of each chapter once. I would start at the beginning and work your way through the book in order. This will get you familiar with every topic and definition. 

Are you limited by time, or want to be more strategic in your efforts? Since they provide you with the percentage of questions by section (according to the 2nd Edition of the CSSGB primer), start from the top of this list, and work your way down, focusing on the sections you don't know as well.

3) After taking the sample questions, mark your book with a post-it note or post-it flag/arrow for keywords and topics that you want to retrieve quickly during the exam. There is an index in the back of the book, but some people find the post-its more helpful. The sections do not always seem intuitive based on their name, so don't think that will be much help during the exam.

4) Answer all sample test questions at the end of each chapter. The questions are based on old test questions, That means:

• They are a good representation of the type of wording and questions you will get on the actual exam.
• They may have been thrown out or poorly worded, so you will get frustrated with some of the answers.

Therefore, don't get too wrapped up in one or two questions. You will notice that reading the question clearly is very important. Don't just skim it and think you understand what they are asking for.

After taking the sample questions, check your answers in the primer, and review the questions you got incorrect. Read the explanation, and see if it makes sense. Go back into the primer and make notes about the question. Often times, there is a similar example in the training material that you can add comments in the margin.

NOTE: You will not be able to bring the practice questions or solution text into the exam. It is open book, so almost everything else you can bring in for reference, except those two things.

If you still aren't sure why the answer was correct, seek out some help from people in your company or network who can help you out. We will be setting up some exam review sessions starting in October 2013, so contact us for dates of online and in-person review sessions.

5) After reading the book, and taking the sample questions, you should feel comfortable knowing if you have a chance at passing. If you feel like you understand most of the content, and are getting most of the questions correct (at least 50% correct on the first time through), then you are probably ready to sign up for the exam. There is no official cut-off or % correct, since it is based on a difficulty rating, but the rule of thumb is around 70% correct. Study and prepare so you will get at least 80% correct, so you don't push your luck.

6) After signing up for the exam, continue working on the problems you struggled with. Some additional training might be helpful, if the primer book is not explaining it very well. Again, check out the free online Green Belt training from BMGi. If you can't find any helpful training on the topic, contact us and we'll point you in the right direction.

7) Read the blog we wrote titled "15 last minute tips before taking an ASQ Green or Black Belt exam" at least one month prior to the exam date. Some of these tips are pretty simple, but it helps to think about everything, and be proactive.

8) Any additional free time should be spent re-reading and reviewing each section, with an emphasis on the sections with the most questions (see Pareto chart above). If you don't know what a Pareto chart is, you should start planning to re-take the exam!

If you feel more comfortable having some reference materials with you (not required), I would recommend borrowing some of the following books from a colleague (or purchase if necessary):

• The Certified Six Sigma Green Belt Handbook

• The Six Sigma Handbook

• Implementing Six Sigma

There is a lot here to remember. Luckily, we have recently developed an "ASQ Six Sigma Exam Reminder System", that will email you as the exam date nears, with these tips and tricks to help you pass the exam.

Good luck! 

Let us know if you have other tips or tricks that worked for you!

Online statistics training from Minitab has great animation and examples

Minitab statistical software is one of the most powerful and popular programs around, especially for those in the Six Sigma realm.

They recently released a suite of online training courses called Minitab Quality Trainer.

The training is very good, much better than what can be done by an instructor in a classroom. That is because the words have been streamlined, and the animation enhances the concepts being discussed. Online training can reduce the training time by 50% or more compared to traditional classroom training. Minitab has a lot of experience teaching these concepts, so it's no surprise. You can view a sample of Quality Trainer on their website.


There are nine chapters, covering the following topics:


Chapter 1: Descriptive Statistics and Graphical Analysis (60 mins)
Chapter 2: Statistical Inference (60 mins)
Chapter 3: Hypothesis Tests and Confidence Intervals (180 mins)
Chapter 4: Control Charts (75 mins)
Chapter 5: Process Capability (100 mins)
Chapter 6: Analysis of Variance (ANOVA) (60 mins)
Chapter 7: Correlation and Regression (60 mins)
Chapter 8: Measurement Systems Analysis (150 mins)
Chapter 9: Design of Experiments (120 mins)



One of the issues with their training is that there aren't any estimated times for each chapter. We like to solve problems, so we took the time to breakdown the chapters and sections, to give you and your employees a better idea how to schedule and plan for the training courses (see above). Completing all nine chapters takes about 15 hours, with some chapters as short as 50 minutes, while others are as long as 3 hours. For a detailed breakdown of each chapter section, download the estimated times here (.XLSX file).

The cost is also very reasonable. For an individual, they can have access to the training for only $30 per month (or $300 per year). If you have a network version of Minitab at your company, you can also add unlimited access to Quality Trainer for only a couple hundred dollars per licensed user.

To learn more about Minitab Quality Trainer, visit their website at http://www.minitab.com/en-US/products/quality-trainer/default.aspx

Free Green and Black Belt training?

BMGi is one of the largest process improvement consulting companies around. I've had some friends attend training from them, and they have had positive comments about them.

Due to their size and reputation, I was a little surprised when they opened up a large amount of their online Lean and Six Sigma training for free.

At first I thought it would be some teaser videos on basic concepts only, and you had to pay for the really good stuff, like SPC, Design of Experiments, and DFSS. However, they have an entire Green Belt and Black Belt program you can take. Did I mention it was free?

We obviously can't compete with that option, so instead we decided to make it easier to figure out which exact modules you should take.

Six Sigma certification is highly sought-after, yet very expensive to obtain. You can either attend a one or two week long course, or you can self-study for hours and hours, in order to pass the certification exam.

ASQ offers a Green Belt and Black Belt certification, if you meet the experience and project requirements.  Since ASQ has one of the more popular certification programs around, we decided to align the Green Belt body of knowledge to the BMGi online modules, so you can learn a majority of the content on the Green Belt exam for free, without taking every single module.

Here is the Green Belt Body of Knowledge, along with the links to BMGi's free online training on that topic.

http://www.biz-pi.com/certification.asp?id=10

To learn more about Green and Black Belt certification, visit our website at http://www.biz-pi.com/certification.asp and answer the questions, to determine if you are ready for the certification or not.

You might be wondering, "what's in it for us"? Why would we promote another company's training material instead of our own?

Learning about a topic is just the first step. After a class, you still need to translate the learning into something personal, that applies to the work you do today. That is where we come in. We can help translate the tools and help explain how they fit into your job or company. When you try and apply the training to your work and get stuck, we can help you out, and get you moving in the right direction. That is the value we can bring with our experience, which is more important than providing education and teaching.

It is much more rewarding for us to help you address a specific problem, than stand up in front of a room and talk about concepts and ideas that may not translate into something useful to you. Don't get us wrong. Training is very important, but it's what happens after the training where the real value and learning comes to fruition, and that's where we want to be involved to help you out.

View the list of content you'll need to know to get your Green Belt certification: http://www.biz-pi.com/certification.asp

If you want help studying for the ASQ exam, check out our helpful guide: 8 steps for passing the ASQ Six Sigma Green Belt or Black Belt exam

How many of the 50 Best Practices for Process Excellence has your company implemented?

Lee Pollock and Mark Kiemele are authors of a new book, Reversing the Culture of Waste – 50 Best Practices to Achieve Process Excellence. The book provides a list of best practices that companies use to become stronger in process improvement. Not every company excels at all 50, but the companies that apply most of the suggestions are much further ahead. You can even assess your company, to see how mature your process improvement approach is today.




The book is divided into 10 chapters, and each chapter identifies a few best practices. Where you see the term "process excellence" you can replace it with your company's initiative (Lean, Lean Six Sigma, Continuous Improvement, etc). Explanations of each best practice are provided in a concise summary, usually 1-2 pages in length.

Chapter 1 - Executive Ownership and Leadership Alignment
1. Establish ownership at the executive level.
2. Develop and communicate the need, vision and plan.
3. Train leadership first.
4. Link compensation to involvement and success.
5. Continuously assess what is working and what is not and adjust.

Chapter 2 - Effective Support Infrastructure

6. Designate a well-respected Deployment Champion early.
7. Commission and use a guiding coalition.
8. Partner with a capable and reputable service provider.
9. Integrate key stakeholders into the plan.
10. Create position descriptions that mandate a pull for excellence.
11. Quickly attain a critical mass of practitioners.

Chapter 3 - Integration with Existing Business Improvement Initiatives

12. Maximize the synergy of multiple initiatives.

Chapter 4 - The Right Projects and Studies and People to Lead Them

13. Establish criteria for project selection and prioritization.
14. Use quick-hitting studies to accelerate results.
15. Select top-tier candidates for first waves of training.

Chapter 5 - Integrated Training and Software

16. Use motivational and experienced instructors and coaches.
17. Keep the software simple and easy to use.
18. Use a blended approach to learning.

Chapter 6 - Financial and Implementation Responsibility

19. Use a consistent, simple and straightforward approach.
20. Generate successes early and communicate them.
21. Plan the service provider's exit strategy.
22. Develop internal subject matter experts.
23. Manage the expectations of every practitioner.
24. Define and use a meaty certification process.
25. Train all ares of the organization.
26. Apply the training immediately.
27. Provide expert coaching on all projects and studies.
28. Scope projects carefully.
29. Establish and follow rules for assessing benefits.
30. Publicize and use savings wisely.
31. Regularly review projects and act based on the assessment.
32. Conduct refresher sessions for leaders and practitioners.
33. Connect and use Champions to upgrade the initiative.
34. Make everyone aware of what is going on.
35. Design and use standardized templates.
36. Anticipate and manage position loss resulting from projects.
37. Include team-oriented "soft" tools.
38. Develop transfer functions to predict, optimize, and assess risk.
39. Make innovation systematic.
40. Solve new problems using trained resources and trumpet successes.
41. Make process excellence part of the human resource succession plan.
42. Integrate process excellence into all mergers and acquisitions.
43. Update the implementation plan based on feedback and results.

Chapter 7 - Reward and Recognition
44. Recognize people who execute successful projects.

Chapter 8 - Enterprise-Wide Knowledge Sharing

45. Establish a project-tracking database and keep it current.
46. Schedule benchmarking sessions.

Chapter 9 - Customer and Supply Chain Involvement

47. Involve suppliers and customers early on.
48. Implement a fact-based process for assessing the Voice of the Customer.

Chapter 10 - Change Management: Leveraging Cultural Strengths and Managing Its Weaknesses

49. View process excellence as a mindset, not just a toolset.
50. Leverage cultural strengths that promote change.




To assess your company on their maturity in process excellence, determine your ranking from 0-2 for each item.

0 = No implementation of that best practice whatsoever.
1 = Some areas exist where it is done
2 = We do that very well  

You can use decimals (like 0.5 or 1.5), but they suggest using integers only. Next, sum up the total score for each chapter, and enter the results on the Air Academy website: http://www.airacad.com/bestpractices.aspx  

Your total points will give you an idea where you rank against 500+ companies involved in a 2011 study. For example, if you scored a 32 or less, you are in the 10th percentile. If you scored a 48, you are in the 33rd percentile. If you scored a 59, you are the 50th percentile. If you scored an 82, you are in the 90th percentile. There were very few companies scoring above 90 (maximum score is 100 points). Exact percentiles are provided in the book.  

After reviewing your scores, we would recommend determining which best practices could provide your company with the biggest gains, and develop an action plan to address the gaps.  

Leave us a comment if you filled out the assessment, and how your company scored.

Reducing your time might seem like lean, but you can easily anger your customers

Lean is about increasing value to your customer. Often times, this requires you to eliminate waste in the process. However, if you don't understand your customer needs, you might sub-optimize the process in an attempt to make your work easier. However, if you are not careful, you can actually ADD waste to your customers, thus decreasing the value you provide. That is the complete opposite impact you intended, even though you had the right intentions.

Here are some good examples of sub-optimization that you can share in training classes or conversations. I'm sure you have some good examples of your own. Please share them in the comments section below. 

Example #1 - Scrap Report
The Finance department provides a weekly and monthly scrap report to the production managers. The data is in a single spreadsheet file, with filters on the top of key columns (work center and manager). Each manager goes in and searches the report to filter by their name, look at the scrap items, and review them. Some of them create their own pivot table to be able to sort and filter all the data. Each month is separated into unique tabs (pretty common in finance reports), which makes it difficult to look at data over the whole year. The finance person did not want to spend an extra 10 minutes each time creating the pivot table report and combining the new data with the existing data for the entire year in one spreadsheet. However, when we look at the full impact of time for the entire company, each production manager is required to create their own pivot table (5 minutes each), or they spend extra time filtering the data (not as efficient as a pivot table), or they completely ignore the report, since they find it hard to analyze. So the finance person saves themselves ten minutes each week, but this time adds at least an hour to the entire organization, and not everyone is taking action on the data, which is an even bigger waste.

Example #2 - Procedure Updates
Each month, an email is generated from the document control group with a list of procedures that were revised recently. At least 1000 people are sent this list. They were asked to provide a quick summary of the change made in each document, so we could decide if it was something we needed to investigate or read in more detail, or if we could ignore it. He said it would add about an hour's worth of his time to do that, so he refused. However, if we assume that 10% of the distribution is actually interested in these changes, that means at least 100 people are clicking each of the procedures and scanning through to find the revision change summary. If we assume that takes 5 minutes to complete, then 500 minutes (8 hours) have been wasted in the company. So the document control group saved themselves one hour of work, but added 8 hours of work to the company, and many people did not get the updates they needed, which is a huge waste. If they did provide a summary, they might actually increase the number of people on the distribution who learn about the revisions, and therefore proceed to click the links to read the updates.

Example #3 - IT help desk ticket
I needed to have a website updated, so I contacted the information technology (IT) person responsible for the task. I have this task performed a couple times per year, so it is infrequent. The individual said they could take care of it, but I need to submit a ticket for them to work on it. I agreed, and called the help desk line to submit the ticket. After 30 minutes of discussion with the help desk support person, I finally got the ticket submitted. I was very frustrated. The company wasted 30 minutes of my time, and 30 minutes of the help desk's time to get the ticket entered correctly. This was due to the complex nature of the work being done. The person who was going to be doing the work could have probably entered the ticket themselves in about 5 minutes, since they knew exactly what was needed to be done. So they saved themselves five minutes of work, but added one hour of waste to two other individuals.

As you can see, the key message is to understand what things you do that are valuable (value added) to your customer, and what things are not valuable (non-value added). Only eliminate the non-value added, or you could make your customer's upset and frustrated.