Publications by Donny Lofland
DATA605 Homework 7
knitr::opts_chunk$set(echo = TRUE) library(tinytex) library(pracma) Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem 1 Let X1, X2, . . . , \(X_n\) be n mutually independent random variables, each of which is uniformly distributed on the integers from 1 to k. Let Y denote the minimum of the \(X_i\)’s. Find the di...
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DATA605 Homework 8
knitr::opts_chunk$set(echo = TRUE) library(tinytex) library(pracma) Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem 11 (p 303) A company buys 100 lightbulbs, each of which has an exponential lifetime of 1000 hours. What is the expected time for the first of these bulbs to burn out? (See Exercise 10.) \[\text{from ...
1803 sym R (357 sym/12 pcs)
DATA605 Homework 12
knitr::opts_chunk$set(echo = TRUE) library(tinytex) Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] WHO 2008 Dataset REgression The attached who.csv dataset contains real-world data from 2008. The variables included follow: Country: name of the country LifeExp: average life expectancy for the country in years InfantSurvi...
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DATA605 Homework 16 -Multivariate Calc
knitr::opts_chunk$set(echo = TRUE) library(tinytex) library(Deriv) library(reticulate) ## Warning: package 'reticulate' was built under R version 3.6.2 Sys.setenv(RETICULATE_PYTHON = "/Users/dlofland/anaconda3/bin/python") Source files: [https://github.com/djlofland/DATA605_S2020/tree/master/] Problem 1 Find the equation of the regression line f...
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DATA605-Final Project
knitr::opts_chunk$set(echo = TRUE) library(tinytex) library(tidyverse) ## ── Attaching packages ──────────────────────────────────────────────────────────────────────────────────�...
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DS621 Homework 1 (Group3)
Overview In this homework assignment, you will explore, analyze and model a data set containing approximately 2200 records. Each record represents a professional baseball team from the years 1871 to 2006 inclusive. Each record has the performance of the team for the given year, with all of the statistics adjusted to match the performance of a 162...
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Data624 - Homework 1 (Timeseries)
Problem 2.1 Use the help function to explore what the series gold, woolyrnq and gas represent. Use autoplot() to plot each of these in separate plots. autoplot(gold) + ggtitle('Daily morning gold prices in US dollars. 1 January 1985 – 31 March 1989.') + xlab('Year') + ylab('Price') autoplot(woolyrnq) + ggtitle('Quarterly production...
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DATA608 - Module 1
Principles of Data Visualization and Introduction to ggplot2 I have provided you with data about the 5,000 fastest growing companies in the US, as compiled by Inc. magazine. lets read this in: library(ggplot2) library(dplyr) ## ## Attaching package: 'dplyr' ## The following objects are masked from 'package:stats': ## ## filter, lag ## The ...
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DATA 624 - Homework 5 (Exponential Smoothing)
Source Code: https://github.com/djlofland/DATA624_PredictiveAnalytics/tree/master/Homework_5 Problem 7.1 Consider the pigs series — the number of pigs slaughtered in Victoria each month. Use the ses() function in R to find the optimal values of \(\alpha\) and \(\ell_0\), and generate forecasts for the next four months. Compute a 95% predictio...
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DATA 621 - Assignment 3 - Crime Logistic Regression
Source code: https://github.com/djlofland/DS621_F2020_Group3/tree/master/Homework_3 Instructions Overview In this homework assignment, you will explore, analyze, and model a data set containing information on crime for various neighborhoods of a major city. Each record has a response variable indicating whether or not the crime rate is above th...
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