Considering Defects and Defectives via the Republican Primary

Cody Steele 19 August, 2015

The difference between defects and defectives lets you answer questions like whether to use a P chart or a U chart in Minitab, so it’s a handy difference to be able to explain. Of course, if you’ve explained it enough times—or if someone’s explained it to you enough times—the whole thing can get a little tired.

Fortunately, a new explanation of defects and defectives is one more way we can entertain ourselves with the candidates from the 2016 Republican Presidential Primary, even though it’s only 2015. Ready? Here we go!


A defective item is not acceptable for use, but when we do a statistical analysis we don’t have to be overly literal. In politics, when we do a poll about whether a voter will vote for a certain candidate, we’re using the same math that we do when we talk about defective items. The voter either votes for the candidate or doesn’t vote for the candidate. The voter is either useful to the candidate or not useful to the candidate, in terms of election results.

So when a Fox News poll reported on August 3rd that 26% of their poll respondents who answered a question about who they would choose in the Republican primary chose Donald Trump, the other 74% of the respondents were defectives—as far as their usefulness to Donald Trump in that poll.

26% respond that they would vote for Trump. The other 74% are of no use to him in this poll.


A defect is any departure from specifications, but a single defect does not make an item unacceptable for use. In fact, an item can have multiple defects and the defects might not even be noticeable to the person who needs to use the item.

People who do not vote for a candidate are defectives from the perspective of their usefulness to the candidate, but might or might not have defects.

An interesting example of defects comes from's Grammar Power Rankings, which check the grammar of candidates’ supporters on Facebook. Grammarly determined, for example, that Carly Fiorina’s supporters wrote comments on her Facebook page that contained 6.3 grammatical errors per 100 words. Individual posts can have a higher or lower rate of defects, but the candidate might not care at all. The post, as an item, is still usable.

Grammar mistakes are good examples of defects. In a Facebook post, they probably can't make a post impossible to use.

Wrap up

If you need a more traditional explanation of defects and defectives, that information is in the Minitab Support Center (plus a lot more).

If you’re in the Assistant, then you can click on “What are you counting” to get an explanation right when you need it. With the support you get with Minitab, you can spend less time looking for answers and more time making decisions.