Tools Archives – Michel Baudin's Blog

Sep 3 2024

Using Regression to Improve Quality | Part I – What for?

In quality, regression serves to identify substitutes for true characteristics that are hard to observe and to find the root causes of technically challenging process problems. It is a major topic in data science, but oddly, the most extensive coverage I could find in the literature on quality is in Shewhart’s first book, from 1931! Later books, including Shewhart’s second, discuss it briefly or not at all. The ASQC, forerunner of the ASQ, published an 80-page guide on how to use regression analysis in quality control in 1985, but has not updated it since.

Regression analysis has been around for almost 140 years and has grown massively in scope, capabilities, and dataset size. Perhaps, it is time for professionals involved with quality to take another look at it.

By Michel Baudin • Data science, Tools • 1 • Tags: Quality, regression, Statistical Process Control

Mar 31 2023

Using videos to improve operations | Part 9 – Updates

It’s been 110 years since Frank Gilbreth first used film cameras to improve processes, 36 years since Kei Abe taught me how to do it with VHS, and six years since my last post about videos. Yet the number of manufacturing companies leveraging this tool remains minuscule. The technical hurdles are long gone, but the human ones are still in place. Managers must make it a priority to make the work easier for operators, and operators need to trust management not to use videos against them. My 2nd post on this subject was about management preparation. It’s doable, if not easy.

This post focuses on the easy part: technical issues. This is not to ignore the hard stuff but to address a few recent challenges. Smartphone cameras, by default, now generate high-definition video files so large that they impede analysis. It is, therefore, a good idea to work with lower resolutions. The software to help with time studies based on video has evolved too, and I am including introductions to a few currently available packages. Readers are invited to share their experiences with these or other tools.

By Michel Baudin • Tools • 1 • Tags: Manufacturing, Process analysis, Video analysis

Oct 8 2021

Sales Forecasts – Part 4. Generating Point Forecasts with Trends and Seasonality

This fourth post about sales forecasts addresses what you actually start with — that is, visualizing the time series of historical sales and generating point estimates for the future. Theyou analyze the residuals to determine the probability forecasts.

What prompted me to review this field is the realization based on news of the M5 forecasting competition that this field has been the object of intense developments in recent years. Some techniques from earlier decades are now accessible through open-source software that can crunch tens of thousands of data points on an ordinary office laptop.

Others are new developments. Thanks to Stefan de Kok, John Darlington, Nicolas Vandeput, and Bill Waddell for comments and questions on the previous posts, that made me dig deeper:

By Michel Baudin • Tools • 0 • Tags: Exponential Smoothing, Holt-Winters, Point Forecast, Probability Forecast, Sales Forecasting, Time Series

Jul 30 2021

Sales Forecasts – Part 2. More About Evaluation

The lively response to last week’s post on this topic prompted me to dig deeper. First, I take a shot at clarifying the distinction between point forecasts and probability forecasts. Second, I present the idea behind the accuracy metric for probability forecasts that Stefan de Kok recommends as an alternative to the WSPL. Finally, I summarize a few points raised in discussions on LinkedIn and in this blog.

All of this is about evaluating forecasts. We still need methods to generate them. There are many well-known, published methods for point forecasts but not for probability forecasts, particularly for sales. This is a topic for another post.

By Michel Baudin • Tools • 2 • Tags: Probability Forecast, Sales forecast

Jul 16 2021

Sales Forecasts – Part 1. Evaluation

When sizing a new factory or production line, or when setting work hours for the next three months, most manufacturers have no choice but to rely on sales forecasts as a basis for decisions.

But how far can you trust sales forecasts? You use a training set of data to fit a particular model and a testing set of actual data observed over a time horizon of interest following the end of the training set period. The training set may, for example, cover 5 years of data about product sales up to June 30, 2021, and the testing set the actual sales in July, 2021.

The forecasters’ first concern is to establish how well a method works on the testing set so that the decision makers can rely on it for the future. For this, they need metrics that reflect end results and that end-users of forecasts can understand. You cannot assume that they are up to speed or interested in forecasting technology.

Forecasters also need to compare the performance of different algorithms and to monitor the progress of an algorithm as it “learns,” and only they need to understand the metrics they use for this purpose.

By Michel Baudin • Tools • 11 • Tags: Kanban, Production planning, Sales forecast

Mar 12 2021

Process capability

The literature on quality defines process capability as a metric that compares the variability of its output with tolerances. There are, in fact, two different concepts:

The ability of a process under nominal conditions to consistently produce output that meets expectations.
The means of assessing it.

By Michel Baudin • Tools • 6 • Tags: Cpk, First-pass Yield, Quality, Rolled Throughput Yield, Run-by-Run, SPC, Yield

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Using Regression to Improve Quality | Part I – What for?

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Using videos to improve operations | Part 9 – Updates

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Sales Forecasts – Part 4. Generating Point Forecasts with Trends and Seasonality

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Sales Forecasts – Part 2. More About Evaluation

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Sales Forecasts – Part 1. Evaluation

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Process capability

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Using Regression to Improve Quality | Part I – What for?

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Using videos to improve operations | Part 9 – Updates

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Sales Forecasts – Part 4. Generating Point Forecasts with Trends and Seasonality

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Sales Forecasts – Part 2. More About Evaluation

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Sales Forecasts – Part 1. Evaluation

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Process capability

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