Use the guidelines to evaluate the study. Discuss flaws that you see in the study. A researcher from an environmental group wishes to gauge political sentiment regarding a proposed environmental law. He obtains a list of 1000 email addresses from an internet provider, uses a random number table to select a random sample of 100 of these addresses, emails the people in the sample asking them "How do you feel about the proposed environmental law which will improve the quality of our air?" He requests that people respond to his question by email. After the study he announces that 72% of Americans are in favor of the new environmental law.

Question

What will be an ideal response?

Answer 1

There is selection bias as the sample was obtained from among people who own a computer. This group may not be representative of Americans as a whole.
Also there is participation bias as the group consists of those who chose voluntarily to respond. People who respond voluntarily are likely to have stronger opinions than the average person.
The wording of the question is not neutral, will probably influence people to say that they favor the proposed law.
The researcher works for an environmental group and is probably strongly in favor of the new law. For this reason the researcher may not be unbiased.