STATS 201/208代做、Data Analysis代写、代做R程序设计、代写R语言

日期：2019-05-28 10:39

STATS 201/208 Data Analysis

Assignment 4, First Semester, 2019

Due: 3pm Thursday 30th May

Instructions concerning this assignment:

We are providing you an R Markdown document called STATS20x_2019_S1_A4.rmd

(available on Canvas) which will have some answers already filled in. You will need to fill in

and complete the rest of the document. The data files you will be using for the assignment are

described in the questions and are available from Canvas. Make sure you put these datasets in

the same place you put the R markdown document because it is going to look for them there.

The first change you need to make to the markdown document is put your name and ID number at the top.

Notes:

This assignment is worth 7% of your final mark and requires a substantial amount of work. Do

not leave it until the last few days.

Late assignments are not accepted unless there is a good reason for an extension being granted

(usually medical requiring a medical certificate).

The total marks for this assignment will be 35 (this includes 4 marks for presentation and

communication) which will be converted to a mark out of 10 for recording. Most of the marks

for assignments will tend to be for interpretation.

There are 4 Presentation and Communication marks for this assignment lost for not doing the

following:

Coversheet. Using and filling in the correct coversheet.

Name and ID number at top of R Markdown document.

Space saving and printing assignment 2-up. Not printing out unnecessary output (listing

data sets or showing erroneous R output). Assignment work printed out in "2-up" layout. 2-up

layout prints 2 pages side-by-side reduced to one page.

Readability. This is for your general communication ability in the assignment. This includes

sentences clearly conveying the correct idea; sentences making sense; comments not being

excessively long or short; conclusions following logically from previous statements.

Use of Natural Language in Executive Summaries. In executive summaries, this is for

discussing the analysis in context, not using variable names, using units when known and

rounding sensibly.

Keeping to the Point in Executive Summaries. In executive summaries this is for not going

into far more detail than required.

It is your responsibility to back up your computer files. If you are using your own computer, it is

your responsibility to ensure that you can access the data and run

R and R Studio well ahead of

the assignment due date. Technical problems outside our control are not accepted as excuses

for submitting coursework late.

Question 1. [11 Marks]

A researcher was interested in comparing e‐mailhabits of adults, depending on their

maritalstatus. They collected the following data from the U.S. GeneralSocial Surveys.

This data is can be found in the file "email.txt", with variables:

email the number of e-mails a person sent in the last 24 hours (day) recorded at

the time of the survey.

marital The persons current marital status (Married , Divorced or Never).

Fit a GLM modelling the number of e-mails sent as counts. Consider all possible pairwise

comparisons of marital status.

Write a Method and Assumption Checks section.

Write an Executive Summary.

Question 2. [20 Marks]

A series of tests were carried out to investigate the effectiveness of two variants of a

insecticide called rotenone. Rotenone is a naturally occurring chemical with insect-killing

properties, obtained from the roots of several tropical and subtropical plant species belonging

to the genus Lonchocarpus or Derris. It is used in home gardens for insect control.

For each test, a number of insects were exposed to a randomly assigned dose of either variant

A or variant B of the insecticide. The number of insects that died and survived in each group

were then recorded.

We want to know the effect of increasing the dosage of the insecticide and are particularly

interested in the effectiveness at a dosage of 1 unit. This is because it is thought that there are

some harmful environmental side effects with high doses of the pesticide. We also want to

know if there is a difference in their effectiveness between the two variants and whether any

difference depends on the level of dosage.

The data is can be found in the file "rotenone.csv", with variables:

Dead The number of dead insects from that particular test.

Alive The number of insects surviving that particular test.

Dose The dose of the poison (e.g., concentration) of the insecticide.

Poison The variant of the poison. Either A or B.

Comment on the plots of the data.

Fit a logistic regression model with an interaction term between Poison and Dose.

Determine whether the model can be simplified (i.e., apply Ockham's razor), and

determine an appropriate final model. (Remember – only drop ONE term from your model

at a time.)

For both variants of the insecticide, use your model to predict the proportion of insects that

will be killed if the dose level is 1.

Write a Method and Assumption Checks section.

Write an Executive Summary.