Question

2. Fill in the blanks: If the mean is distribution is skewed to the (smaller/equal/greater) than the median, the (left/right). 3. A company that sells sandwiches is interested in calculating the average rating that consumers give their sandwiches. Evaluate each of the following sampling methods by stating a) if they suffer from bias (yes or no), b) if yes, what type of bias (selection, response, both). Explain your answers. a. Asking every person who walks out of their store on a Friday to rate the sandwich b. Printing a message at the end of all receipts that include a sandwich purchase asking people to go to a website to rate the sandwich. c. Offering a discount at the moment of purchase) to consumers who agree rate the sandwich before leaving the restaurant. d. Suggest a different sampling method and discuss the sources of potential bias that it suffers from, if any.

Answer 1

2. If the mean is smaller than the median, the distribution is skewed to the left.

A mean being smaller than median means that there is more repetition on the right side which leads to higher median and lower mean.

3.

a. this suffers from selection bias as not every one who walks out of store will have bought a sandwich.

b. Response bias. Many people are not going to be persuaded to rate on the website. Even worse, those who dont like the sandwich are likely to respond on the website.

c. both. Not all people are going to agree to respond, then some of those who agreed wont respond when leaving and those who respond are likely to rate it good due to the discount.

d. A better way of sampling would be the waiter asking the customers for rating after they have eaten the sandwich. This will mean very few will refuse to respond. Though the chance of those responding who didn't like is still slightly higher here, it is lesser than the website method.