Author: Len Greski

This repository contains content developed during my time as either a student or Community Mentor in the Data Science Specialization from Johns Hopkins University that is offered over Coursera. A number of people have developed content to help students work through the nine courses in the specialization. The main index for this content is datasciencespecialization.github.io.

As a participant and Community Mentor in courses in the curriculum, there are patterns of similar issues experienced by students. Migrating the content to github will facilitate reposting it to new runs of courses within the curriculum. This will make it easier for students to have access to the experiences from prior students without me having to cut and paste the content into Discussion Forums, which are the primary mechanism for communication between students and with TAs.

The remainder of this document serves as a directory of the content, aligning individual documents with the course(s) for which the content is relevant.

1. Configuring RStudio to work with git / github - Mac OSX
2. Configuring RStudio to work with git / github - Windows 7, 8, and 10
3. Using Editor Modes in Discussion Forum Posts
4. Buying a Computer for Data Science

General commentary about the course, R programming in general, and R in relationship to other statistics packages.

1. Commercial Statistics Packages: An Historical Perspective
2. Configuring RStudio to work with git / github - Mac OSX
3. A Data Frame is Also a List
4. Forms of the Assignment Operator
5. Forms of the Extract Operator
6. S Objects, R Objects, and Lexical Scoping
7. Thinking in R versus Thinking in SAS
8. Strategy for the Programming Assignments
9. Why is R More Difficult than SAS?
10. R Onboarding for SAS Users
11. References for R Programming Provides a list of references for R programming, ranging from beginning to advanced topics.

1. Assignment 1: Breaking Down Pollutantmean
2. Assignment 1: A SAS Version of Pollutantmean
3. Assignment 2: Demystifying makeVector
4. Assignment 2: makeCacheMatrix as an Object
5. Assignment 2: Grading the SHA-1 Hash Code
6. Assignment 3: Functions to Sort Data Frames

1. Common R Mistakes: Overwriting R Functions with Output Variables
2. Permanently Setting R Working Directory Link to R-bloggers.com article that explains how to set your working directory permanently in R (instead of RStudio)
3. Creative Use of R: Downloading Course Lectures Article illustrating how to use R to automate the download of lectures from Data Science Specialization courses, such as R Programming. Techniques used in this article are helpful to make research reproducible, as required for courses like Getting and Cleaning Data and Reproducible Research.

1. R vs. Python: 2016 Survey of Software used for Data Science Overview of results from a 2016 KDNuggets Software Poll, written by Gregory Piatetsky. The follow up article with expanded analysis is What Big Data, Data Science, Deep Learning software goes together, also on kdnuggets.com.
2. Scaling R for Data Science August 2016 article by Federico Castanedo explaining three ways to scale R.
3. Lexical Scoping and Statistical Computing Article by Robert Gentleman and Ross Ihaka at the University of Auckland describing how lexical scoping works, and why it is valuable in statistical computing.

1. Real World Example: Reading American Community Survey data
2. Strategy for Reading Files & APIs / Quiz 2

1. Assignment 2 Checklist

1. Reference Materials for Statistical Inference Start here if you're looking for help on the statistical techniques taught in this course.
2. Using MathJax with Discussion Forums, R Markdown, and Github Pages
3. Power Calculations: Optimal Sample size
4. Permutation Tests Explained

1. Exponential Distribution / Central Limit Theorem - Assignment Checklist
2. ToothGrowth Analysis - Assignment Checklist
3. Exploratory Data Analysis in ToothGrowth Assignment, explaining the exploratory data analysis requirement for students who have not taken the Exploratory Data Analysis course prior to taking Statistical Inference.
4. Accessing R Code from an Appendix in Knitr
5. Theoretical Variance of Sampling Distribution of the Mean
6. Kable Tables with Data Frames illustrates how to display a custom table in a knitr() document by creating a data frame to contain the information to be rendered with kable().
7. Installing MiKTeX on Windows 10 / Generating a PDF with knitr

1. Why does sum of errors * X equal 0?
2. Using MathJax with Discussion Forums, R Markdown, and Github Pages

1. Week 4: Combining Predictors Math Explained
2. Course Project - gh-pages Setup with RStudio
3. Course Project - Improving Runtime Performance of Random Forest Models with caret::train()
4. Course Project - Predicting Test Scores based on Training Model Accuracy

1. Configuring shinyapps.io Application Timeout

1. Tips for New Community Mentors A list of tips for new mentors supporting the Data Science Specialization, ranging from when to direct students to paid / professional resources such as the Coursera Learner Help Center, to how to optimize the value of content that is posted by mentors.