Wednesday HW!

Tonight please complete the "Analyzing Contexts" homework provided in class (there's no title on the paper though) or below!

Homework:

• For each statistical study below identify the following:
• The population: the population is the "whole group" that we're trying to generalize to
• Think: what "big group" does our sample of people represent?
• The population parameter of interest: the parameter of interest is the "number" that we're trying to figure out! (this will likely be a percentage or mean)
• Think about the data you're collecting...
• If you're collecting categorical data, the parameter of interest is a percentage
• If you're collecting quantitative data, the parameter of interest is a mean (average)
• The sampling frame: sampling frame refers to all of the possible people/things that could have been sampled
• The sample: the sample refers to the actual group of people/things that we sampled, or the group of people/things that we actually got our data from!
• The sampling method: in your own words (no fancy vocab...yet) describe how they chose their sample of people/things
• Potential sources of bias or problems in generalizing: Consider this study--are there any major issues/flaws in the way this data was collected? Describe any issues/problems that might arise with this method of data collection
• Bias exists if some group of people or some response is over or under represented in a sample...
• So, think about this (for each scenario)--would some response/group be over or under represented with this sampling method? Who? Why?

1. A question posted on the Lycos Web site on 18 June 2000 asked visitors to the site to say whether they thought that marijuana should be legally available for medicinal purposes. 
2. Hoping to learn what issues may resonate with voters in the coming election, the campaign director for a mayoral candidate selects one block from each of the city’s election districts. Staff members go there and interview all the residents they can find.
3. Dairy inspectors visit farms unannounced and take samples of the milk to test for contamination. If the milk is found to contain dirt, antibiotics, or other foreign matter, the milk will be destroyed and the farm re-inspected until purity is restored.

Here's an example you can use for some help:

Context: Researches waited outside a bar they had randomly selected from a list of such establishments. They stopped every 10th person who came out of the bar and asked whether he or she thought drinking and driving was a serious problem.

Population: all people who are of age to go to bars (adults) in this state/region

Population Parameter of Interest: the percent of adults who think drinking and driving is a serious problem

Sampling Frame: all people at the bar on that day/night (we could've potentially surveyed any person at the bar that night)

Sample: the people at the bar who we actually spoke to/surveyed (every 10th person who came out of the bar)

Sampling Method: we stopped every 10th person on their way out of the bar and surveyed them

Potential Sources of Bias/Problems that May Arise: in this case we're surveying people who are leaving a bar and are possibly about to drink and drive; this may overrepresent people who think drinking and driving isn't a serious issue

For more examples look at any of the odd problems 1-9 on page 289 and check your answers in the back of the book!