Lab Assignment #2 for Chapter 7 MATH
1342 – Statistics
Instructor: David Katz
This lab assignment is to analyze a current events article that uses statistics to verify a margin of error. Limit yourself to one short article that includes a survey or opinion poll (i.e., a confidence interval as in chapter 7). Your current event assignment should include these parts:
1) Copy of the Article – you may look for a short article on an opinion poll or survey in the newspaper, Internet, or similar source. You may even use a memo or policy document from your work. For starters, try these sources:
2) Citation Information – state the article’s title, publisher, author(s), date of publication, and URL if available.
3) Summary of the Statistics Problem - summarize in 3 or 4 sentences the confidence interval (i.e., the survey/opinion poll) included in the article. Make sure the opinion poll contains the number of people surveyed, the sample proportion, and the margin of error.
4) Verification of the Statistical Method – show the mathematics behind the confidence interval based on the given information in the article. Be sure to verify the necessary assumptions of section 7-2 (e.g., is the survey based on a random sample, is sample size large enough? See p.320). Next, use the formula for margin of error to compute: the critical value, confidence level, and the significance level.
5) Conclusion – write a one or two sentence conclusion that re-states the confidence interval estimate of the true value of the population proportion p using a compound inequality (e.g., The 95% CI estimate of the proportion of people in favor of …. is 45% < p < 49%, etc.).
How You Are Graded
(e.g., 48 out of 50 total points equals a grade of 96):
|
Item |
Points |
|
Citation, or Copy of Article |
5 |
|
Summary of Article |
5 |
|
State that sample data was from a random group of
individuals |
5 |
|
Verify and state that sample size is large enough |
5 |
|
Break the problem down into two categories (e.g., for or
against) |
5 |
|
State the n, p-hat,
q-hat, x, and margin of error (E) |
5 |
|
Compute critical value (z) |
5 |
|
Compute the significance level (a) |
5 |
|
Compute confidence level (hint: C-Level = 1 - a) |
5 |
|
Re-state confidence interval as compound inequality |
5 |
|
TOTAL POINTS |
50 |
Typing the report is not necessary, but remember neatness counts! If I cannot read your report, I cannot grade it! Your finished report should be about 1-2 pages.
I encourage you to work together with your classmates to help write up the lab and/or find good articles with data tables. However, please don’t just copy verbatim a classmate’s lab report and hand it in as your own!
Some Hints on the Mathematics
- Be sure to verify the pre-requisites necessary to use the confidence interval formulas for estimating a proportion. For example, one pre-requisite is that the number of successes and failures must be greater than five. Your lab report should include work similar to this:
Note that 
Because
the number of successes and failures is greater than five, we can conclude that
the sample size is large enough and that we can use the confidence interval
methods in the textbook to estimate the population proportion.
- To compute the critical value used, start with the formula for margin of error, and then use your elementary algebra skills to solve for the critical value z:
After you substitute the given information into this formula, you should be able to calculate the critical value z on your calculator.