February 1, 2016

Assignment

Background

This assignment requires you to perform inferential techniques on the dataset(“Smartphone.xlsx”)used in Assignment 1 and then report your findings to a person with little or no knowledge of statistical data analysis.
Part 1 : Data Analysis(mostly handwritten —a maximum of 8 pages);
Part 2 : A reply to the Senior Editor’s questions in the form of a memorandum(maximum of two pages).
Scenario

As was the case in Assignment 1, you are playing the role of Linh Nguyen,an analyst at Consumer Magazine. Lasitha Dharmasena,one of the senior editors at the magazine, has written to you again regarding the Smartphone dataset. Hermemorandum is reproduced below.
For Attention: Linh Nguyen, Analyst 14/12/2015
From: Lasitha Dharmasena,Senior Editor
Regarding: Further analysis of Smartphone dataset

Dear Linh

Thank you for your earlier response. Ialso need the following information.

1. Please provide me with a 90%confidence intervalfor :
a. the mean monthly bill for ALL smartphone users?
b. the proportion of ALL smartphone users who are on a post-paid plan?

2. We wrote previously that, on average,smartphone users spend more than \$61.50 on their monthly bill. Please check if this is still the case (at 5% significance).

3. We also wrote previously that less than 65% of smartphone users are on a post-paid plan. Please verify that this is still the case(at 5% significance).

4. Please checkif there is a difference in the mean monthly billbetween ALL male and ALL female smartphone users(at 90% confidence).
5. The dataset is a sample of 150 users.What sample size would be needed in order to be able to estimate:
a. the mean monthly bill for ALL smartphone users to within \$2.50, with 90% confidence?
b. the proportion of ALL smartphone users who are on a post-paid planto within 4%, with 90% confidence?
(NOTE TO STUDENTS 2: In part a, you can assume s = \$45.)

I look forward to your response.
Sincerely
Lasitha Dharmasen

Part1: Data Analysis:

You will need to perform a number of manual calculations,using thedata set“Smartphone.xlsx”.Some of these calculations will be based on your answers in Assignment 1.As for Assignment 1 your data analysis section must be no more than 8 pages.
Part 2: Response to Lasitha

As for Assignment 1,your response must be in plain language and a maximum of two pages.
Variable : Variable descriptions:

Respondent Respondent number (not relevant for analysis)
Income Income of the Smartphone user in dollars (\$)
Gender Gender of the Smartphone user
Age Age of the Smartphone user in Years
State State where the Smartphone user resides
LivingStatus Respondent’s living status
LandLine Owns a landline phone?
MobilePrimary Primary phone is mobile phone?
PostPaid On a post-paid plan? (No = pre-paid)
MonthlyBill The amount spent last month on the Smartphone in dollars (\$)
MonthlyCap The monthly Smartphone cap in dollars (\$)
PercentForWork Use of Smartphone for work (as a % of total use)
Calls The number of calls made last month
SMS The number of text messages sent last month
MMS The number of multi-media messages sent last month
Data The data allowance on the Smartphone in MB
OnlinePurchase Used the Smartphone to purchase an item online
SocialNetworking Used the Smartphone to visit a social networking site
MonthlySocialNet The number of visits to social networking site using the Smartphone