Testing over time

I’ve been using Google Books nGram a lot recently whilst I research some topics for blog posts, books, articles and other writing. It’s a great way of searching on a term and then finding related books. In fact, it’s so good that my impossibly large reading list has grown from 1498 books to 2200+. I know…I will never read them all, but I’ll have a good go.

So I thought I would share with you some of the graphs nGram created relating to Software Testing terms.

If you’ve never used nGram then head over to Google Books nGram page and have a play around. The year data it returns in the table at the bottom are clickable and will lead you to the books that mention your search term…let your expanding reading list begin 🙂

nGram basically works by scanning millions of books for your search term and then providing you with a line graph of that terms use over time.

When you enter phrases into the Google Books Ngram Viewer, it displays a graph showing how those phrases have occurred in a corpus of books (e.g., “British English”, “English Fiction”, “French”) over the selected years. – from the nGram page

Here’s one for the term “software testing”:

(clicking on each image will show a larger one)

As you can see around the 1960’s and 1970’s the term really took off and has grown in it’s use through the last few decades.

Here’s another one, this is “test automation”


Again, the term really comes in to use in the 1960’s and grows dramatically, but interestingly it drops off in 2000. Did we see a drop in books about automation around then? Or did we start calling it something else? Or some other reason?

Here’s “quality assurance”. Same sort of trend as Software Testing and Test Automation


Here’s “exploratory testing”

Interestingly the term has been around for a while but when clicking through to search for the books you get some very interesting suggestions. Try the search and click through to the books from the 1800 – 1949 – some fascinating looking books.


“Test Management” sees a similar trend to “software testing”:


What about “boundary value analysis”



“performance testing” shows a similar growth:


“Usability” sees a later rise but the numbers show it was a growing topic of interest between the time ranges. It’s a popular topic now, but nGram only appears to go up to 2008.


You didn’t think I’d do all of these search terms without searching for “certified tester” did you?


Interestingly the term has been around for a while and in the early books it referred to various different roles and responsibilities, mostly associated with science, schooling and adjudication. It grew hugely in the 1980s, again mostly from schools and education before dropping greatly in the 1990’s – possible as school systems went through reform and as electronic marking and computers came to education. It took off again in the 1990’s and 2000’s with a load of books about ISEB and ISTQB certification.

This is pretty vague data but the beauty of nGram is the book search off the back of the term. Clicking through the dates you can grow a large reading list over time of how a term (i.e. idea or process) changes. It’s also a nice way to see what the historical trend in books is for a term. It doesn’t show me (at the moment) anything of significant value; we know the software development industry kicked off over the 1950’s, 60’s, 70’s and 80’s so it’s to be expected that there are growing numbers of books over this period.

But even though I can’t draw anything direct from the data doesn’t mean it’s pointless. I find it interesting, I like to stumble across new books, I like to play with tech and I like to find try things that might later down the line inspire new ideas for me.

Why not have a play around and see whether you can find anything interesting about Testing by using nGram.


4 thoughts to “Testing over time”

  1. Hi Rob
    Very cool post! Enjoyed reading it a lot. I had almost forgotten about nGram and I didn’t know you can see the books the results are based on. And: Happy reading with your 2200 books. Just one book a week and you’re done in 42.3 years 🙂

Comments are closed.