Exam 4: How to Get a Good Sample

What does the word 'unit' mean, in statistical terms?

For Questions use the following narrative Narrative: Valentine spending Suppose you want to find out how much money each adult will spend on Valentine's Day this year, on average. -{Valentine spending narrative} Suppose you go to a local mall the day before Valentine's Day and ask the first 50 people you see.What type of sample are you getting here?

For Questions use the following narrative Narrative: Exit poll Suppose a recent election exit pollster reports that "Forty-eight percent of the voters polled said they voted for Candidate A.The margin of error for this survey is plus or minus 2.5 percentage points." Assume the exit poll was designed and conducted correctly. -{Exit poll narrative} About how many people were sampled?

The __________ is the entire collection of units about which we would like information; the __________ is the collection of units we actually measure.

For Questions use the following narrative Narrative: Boat show The annual Vacation & Boat Show in Columbus, Ohio offers four types of attractions: boats, fishing gear, outdoor equipment, and vacation planning services.Tickets sell for $6 per person, and children under 5 get in free.This year the show organizers want to find out which attraction was most popular, so they surveyed 100 people at random who attended the show, and asked them.The results showed that 67% of them liked the boats best. -{Boat show narrative} Specify the population.

What is wrong with using a list of registered voters to predict election outcomes?

Which of the following is a research strategy that involves the researcher manipulating the participants' environment in some way?

For Questions use the following narrative Narrative: Exit poll Suppose a recent election exit pollster reports that "Forty-eight percent of the voters polled said they voted for Candidate A.The margin of error for this survey is plus or minus 2.5 percentage points." Assume the exit poll was designed and conducted correctly. -{Exit poll narrative} What can be concluded about Candidate A?

It is difficult to survey certain groups of people, such as the homeless population, because they don't have addresses, phone numbers, or residences.Explain how you would select a sample from the homeless population in your city, and comment on how 'random' you feel it would be.

Many large surveys use a combination of sampling methods, applying them one at a time.This is called a (an) __________ sampling plan.

For Questions use the following narrative Narrative: Boat show The annual Vacation & Boat Show in Columbus, Ohio offers four types of attractions: boats, fishing gear, outdoor equipment, and vacation planning services.Tickets sell for $6 per person, and children under 5 get in free.This year the show organizers want to find out which attraction was most popular, so they surveyed 100 people at random who attended the show, and asked them.The results showed that 67% of them liked the boats best. -{Boat show narrative} The 100 people who were surveyed make up which group?

A (an) __________ is a survey in which the entire population is measured.

Assume you have a sampling frame of your entire population of interest, which is comprised of 100 people's names.Which of the following sources could not be used to select a truly simple random sample of 10 people from this population?

For Questions use the following narrative Narrative: Apartment complex Suppose you want to survey the opinions of the residents of an apartment complex.The complex contains 100 buildings, each with 8 units per building, for a total of 800 units.You decide to sample 160 of the units. -{Apartment complex narrative} Suppose 50 of the buildings (400 total units) are for singles, and 50 buildings (400 units) are for non-singles.You randomly select 80 single units and then you randomly select 80 non-single units.What sampling method did you use?

Give a situation where a simple random sample would be impossible or not feasible, and a systematic sample would be necessary.

Why do researchers conduct experiments that are randomized (that is, participants are randomly assigned to the groups being compared)?

What is one advantage of a cluster sample over a simple random sample?

Why should you be suspicious of a survey that was conducted on a random sample of 2,000 people but was done in one night (this is typical of the 'instant polling' that goes on in the media).

You have 15 employees working for you: Bob, Sue, Jim, Alex, DJ, Ann, Leslie, Eric, Deb, Tom, Clint, Richard, Tami, Ellen, and Katie.Use the following set of random numbers (generated from the computer program called Minitab) to take a simple random sample of 3 employees to serve on the donut committee: 1453131401146111619116112912015.Which employees got chosen for the donut committee? (Keep the employees in the order given when you assign numbers to them and do not start numbering with 0, start with 1.)

Which of the following types of samples should be avoided at all costs?