Suppose you participate in an instant poll' on an Internet ...

[go.lag]

Suppose you participate in an instant poll' on an Internet website which asks, What is your favorite network TV program at 8 pm (Eastern time) on Thursday night? After answering the question, you look at the results of the entire poll, and find that 6,423 people have responded to it. Should the results of this poll be a good indicator of what the most popular network TV program is on Thursday nights at 8pm (Eastern time)? Explain why or why not.

Question 2

Suppose you want to determine whether taking vitamins every day helps people lose weight. You survey 200 people who had been on a weight loss program for six months, and ask them whether or not they take vitamins every day, and how much weight they lost. Suppose you found that the people who lost the most weight were more likely to have taken vitamins every day. Does this mean vitamins caused the additional weight loss? Explain why or why not.

[xthemafja]

Answer to Question 1

NO. THE SAMPLE OF 6,423 PEOPLE IS A CONVENIENCE SAMPLE, AND IS NOT A REPRESENTATIVE SAMPLE OF THE POPULATION OF ALL TV WATCHERS.

Answer to Question 2

NO; THIS WAS AN OBSERVATIONAL STUDY, NOT A CONTROLLED EXPERIMENT. OTHER FACTORS COULD EXPLAIN THE WEIGHT LOSS, SUCH AS A HEALTHY LIFESTYLE (PEOPLE WHO ARE HEALTH CONSCIOUS MAY BE MORE LIKELY TO TAKE VITAMINS).

[go.lag]

Excellent

[bulacsom]

Gracias!