How to identify sources of bias in an experiment Practice Test

A randomized double-blind experiment in which test subjects are assigned to either a placebo or a therapeutic agent that is used to improve metabolism.

A survey of the number of people that watch online TV conducted using email.

A randomized double-blind experiment in which there are two experimental groups: Group A receiving a small dose of a particular drug and Group B receiving a large dose of a particular drug.

A survey of how many people enjoy shopping conducted at a shopping mall.

None of these examples contain any potential bias.