Trendlines – Lean Six Sigma Moneybelt

Improvement Insights Blog

Posts tagged "Trendlines"

Trends Are Not Always Improvements

Line charts with trend lines can be misleading. They can provide a kind of “false positive” that implies improvement where there is none. Here’s why:

“Hi, I’m Jay Arthur, author of “Agile Process Innovation.”

“I go to all these trade shows and I see a lot of poster presentations but they’re using line charts and then they draw a trend line through them and then they say, “Oh, we made an improvement.” No you didn’t. If it doesn’t really fit the line very well, if your goodness-of-fit metric is less than 80%, I’m not buying it. But nobody gives me a goodness-of-fit metric called r-squared, they just show me a line graph or a bar chart and then they show a little line through it.

Posted by Jay Arthur in Improvement Insights.

Trendlines Are Rarely Improvements

At the 2018 Magnet Nursing conference in Denver, I saw many improvement posters using line or bar charts with an added trend line to show improvement. Unfortunately, few of the trends were valid. Here’s why:

Posted by Jay Arthur in Improvement Insights, QI Macros, Statistics.