# Confidence Intervals-Statistics and Probability

**Confidence Intervals-Statistics and Probability**

To produce a successful project you must: Background: For this assignment, you will use a StatCrunch file containing the survey results dating back to 2004 for two questions from the GPSS. The first asks, “In politics, as of today, do you consider yourself a Republican, a Democrat or an independent?” If a respondent identifies as independent, a follow-up question is asked, “As of today, do you lean more to the Democratic Party or the Republican Party?” The data in the last two columns of the file contain the combined figures of party identifiers and leaners. Each Gallup survey that is part of this series requires at least 1000 respondents. For the purpose of this assignment, we will assume that every survey had exactly 1000 respondents. To access the StatCrunch file, follow this link: Party Affiliation Data (Links to an external site.) Assignment/Instructions: STEP 1: Ask a question involving the change in party affiliation for one party between two dates. For example, I could ask, “Has the proportion of adults nationwide who identify as democrat changed from June 2019 to June 2020?” STEP 2: Look up the two proportions corresponding to your question in the StatCrunch data file and report them in your document. For my example, I will say, “According to the Gallup Poll given in June 2019, 29% of adults identified themselves as democrat and in June 2020, 33% of adults identified themselves as democrat.” STEP 3: Use StatCrunch to find a 95% confidence interval for each proportion using n = 1000 and copy the results into your document. For my example, I would use ˆ=0.29p^=0.29 and n = 1000 to find the first confidence interval, and ˆ=0.33p^=0.33 and n = 1000 to find the second confidence interval. STEP 4: Interpret each confidence interval that you found in Step 3 and answer your question using what you know about confidence intervals. For this step, write a thoughtful paragraph that gives clear interpretations for each of your intervals separately and a reasoned answer to your question using the language and concepts involved with confidence intervals of proportions. This step is where you show that you thoroughly understand this concept and therefore it carries the most points towards your grade for this project. This assignment should receive a full 35 points possible for this assignment. Confidence Intervals This criterion is linked to a Learning OutcomeStep 1Ask a question involving the change in party affiliation for one party between two dates. Full Marks Question includes the political party and dates that are being investigated. Partial Credit Party not given or dates are not clear. No Marks Missing 5 pts This criterion is linked to a Learning OutcomeStep 2Look up the two proportions corresponding to your question in the StatCrunch data file and report them in your document. Full Marks Two proportions are given along with their corresponding date. Partial Credit Two proportions are given but no mention of which proportion corresponds with which date. Partial Credit Only one proportion given. No Marks Missing 5 pts This criterion is linked to a Learning OutcomeStep 3Use StatCrunch to find a 95% confidence interval for each proportion using n = 1000 and copy the results into your document. Full Marks Both confidence intervals are given along with corresponding date and they are both correct. Partial Credit Both confidence intervals are given but it is obvious that StatCrunch was not used. Partial Credit Both intervals are given but one is incorrect. OR Only one confidence interval is given and it is correct. Partial Credit Both confidence intervals are incorrect. No Marks Missing 5 pts This criterion is linked to a Learning OutcomeStep 4Interpret each confidence interval that you found in Step 3 and answer your question using what you know about confidence intervals. Full Marks Each confidence interval is interpreted correctly and the final conclusion is correct. Partial Credit Both intervals are interpreted correctly, but final conclusion is incorrect. OR One or both intervals are interpreted incorrectly but final conclusion follows correctly from misinterpretations. Partial Credit Both interpretations are missing but final conclusion is correct. Partial Credit One or both intervals are interpreted incorrectly and the final conclusion does not correspond with the misinterpretations. Partial Credit Interpretations are missing and final conclusion is incorrect. No Marks Missing 20 pts Total Points: 35 Requirements: As long as necessary Read and follow the instructions carefully. Give yourself sufficient time to work on the project. Write clearly, using appropriate statistical terminology and correct mathematical notation. College-level writing is expected, as is the use of proper grammar. Use StatCrunch to complete all calculations and graphs. Create original work. Submit a professional report that is typed and formatted and organized well.

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