1/2 Econ 3818 Spring 2020 R exercise 3
Order ID: 89JHGSJE83839 Style: APA/MLA/Harvard/Chicago Pages: 5-10 Instructions:
on Canvas as a pdf file. Write up your answers and paste the R code used in a word document. Separate the R code above and below by two asterisk (**). Copy and paste all plots generated into the word document. Saved the document as a pdf and submit it via Canvas. You may work in groups of three (but no more than three!) but every
person has to submit a file individually. If you worked in a group, please put the name of all group members at the top of the text file. R has several functions built-in that can
be used to calculate probabilities associated with known probability distributions. When in doubt, dont forget that you can always type help(function) for documentation! For
example, help(qnorm) might help for question 1. 1. You sample 100 peoples showering habits and find the average shower time is 12.2 minutes. Given that the population
variance shower time is 15, use the qnorm() command to construct an 86% confidence interval for a sample mean. Make sure you are using qnorm() correctly. Note: qnorm()
returns the critical value Z corresponding to the limit of the left tail containing the probability that you state. For a C=90% percent confidence interval, you want 5% in each tail,
i.e. Pr=(1-C)/2=0.05. so you would use qnorm(0.95). See file Rday3.R on Canvas for more details. 2. Load the housing data weve been using: housing_df<-
read.csv(“https://mattbutner.github.io/data/housing_df.csv”) Use a combination of the mean(), sd(), length(), qnorm(), and sqrt() functions to construct a 90% confidence interval for the mean of the CRIM variable (assume that the standard deviation in the population is the same as the standard deviation in our sample). Interpret the confidence
interval. 3. Download the file CI_sim.R from Canvas. This file simulates a bunch of random samples of the same size, constructs the mean and a confidence interval for each
sample, and reports the percent of the confidence intervals that capture the true population mean. Make sure you have sample_size <- 100 num_samples <- 50 ci_level <-0.95
set up in the beginning of the document. You will need to install the user written package ggplot2. To do this, type install.packages(ggplot2) into the console before you run
the R script. You will need to be connected to the internet. For more information, see https://ggplot2.tidyverse.org/.2/2 No need to provide the R code for the following
questions. a. Suppose you increase the sample size from 100 to 200. i. What happens to the width of the confidence intervals? ii. Does the true population mean fall inside more of the confidence intervals? b. Return the sample size back to 100. Now change the number of samples from 50 to 100. i. How does this change the percentage of the
confidence intervals that capture the population mean? ii. As you increase the number of samples towards infinity, what percentage of the confidence intervals will capture the
true population mean? c. Return the number of samples back to 50. Now change the confidence level to 0.8. i. How does the width of the confidence intervals change? ii. Does
the percentage of confidence intervals that capture the population mean increase or decrease? 4. You started taking the bus to work. The local transit authority says that a bus
should arrive at your bus stop every five minutes. After a while, you notice you spend a lot more than five minutes waiting for the bus, so you start to keep a record. You spend
the next two months recording how long it takes for the bus to arrive to the bus stop. This give a total of sixty observations that denote the number of minutes it took for the bus to arrive (rounded to the nearest minute). These observations are hosted at https://mattbutner.github.io/data/bus_stop_time.csv a. Load that dataset into R as a data
frame titled bus_stop_time using the read.csv() command. b. Create a histogram of the time_until_bus variable. Would you say that five minutes is a reasonable guess for the
average arrival time based on this picture alone? c. Create 95% confidence interval for the bus arrival times using the z distribution. Does 5 minutes fall within the 95%
confidence interval? (assume that the standard deviation in the population is the same as the standard deviation in our sample). 5./! This questions had to be answered independently by every student, even if the rest of the assignment was done in a group. Identify, and download, the data set you plan on using for the R data project. Verify there is at least fifty observations, three quantitative variables, and two categorical variables.
1/2 Econ 3818 Spring 2020 R exercise 3
RUBRIC
Excellent Quality
95-100%
Introduction 45-41 points
The background and significance of the problem and a clear statement of the research purpose is provided. The search history is mentioned.
Literature Support
91-84 points
The background and significance of the problem and a clear statement of the research purpose is provided. The search history is mentioned.
Methodology
58-53 points
Content is well-organized with headings for each slide and bulleted lists to group related material as needed. Use of font, color, graphics, effects, etc. to enhance readability and presentation content is excellent. Length requirements of 10 slides/pages or less is met.
Average Score
50-85%
40-38 points
More depth/detail for the background and significance is needed, or the research detail is not clear. No search history information is provided.
83-76 points
Review of relevant theoretical literature is evident, but there is little integration of studies into concepts related to problem. Review is partially focused and organized. Supporting and opposing research are included. Summary of information presented is included. Conclusion may not contain a biblical integration.
52-49 points
Content is somewhat organized, but no structure is apparent. The use of font, color, graphics, effects, etc. is occasionally detracting to the presentation content. Length requirements may not be met.
Poor Quality
0-45%
37-1 points
The background and/or significance are missing. No search history information is provided.
75-1 points
Review of relevant theoretical literature is evident, but there is no integration of studies into concepts related to problem. Review is partially focused and organized. Supporting and opposing research are not included in the summary of information presented. Conclusion does not contain a biblical integration.
48-1 points
There is no clear or logical organizational structure. No logical sequence is apparent. The use of font, color, graphics, effects etc. is often detracting to the presentation content. Length requirements may not be met
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1/2 Econ 3818 Spring 2020 R exercise 3