Main page content

logic: biased or suppressed data

These errors in logic both involve the misuse of data. A writer who resorts to biased data collects evidence from sources on only one side of the argument. A writer who suppresses data chooses data selectively, ignoring evidence that doesn’t support the conclusion he or she wants.

Example of biased data:

“More than 85% of people surveyed believe that the summer break for secondary school students is too short. Therefore, the academic year should be reduced to allow for a longer vacation.”

[The people surveyed were all secondary school students. We can predict that most of them would prefer a longer vacation! Therefore, they represent only one side of the argument, and the sample is biased.]

Example of suppressed data:

“This new product has passed several tests. It meets safety standards and is ready to go on the market.”

[The argument sounds good on the surface–but in this case, the writer has focused on positive test results only and has ignored a small number of tests showing evidence of risks. The writer has therefore suppressed important data.]

In building a logical argument, it is important to be sure that all the facts from both sides of the argument have been fairly presented.

Search by related themes

Want to learn more about a theme discussed on this page? Click on a link below to see all the pages on the Language Portal of Canada that relate to the theme you selected. The search results will be displayed in Language Navigator.

Date modified: