gravatar

DragonflyStats

Kevin O'Brien

Recently Published

Logistic Regression with R -Part 1
Introduction to Logistic Regression and Implementation of logistic regression models with R
Repeatability
The Importance of Repeatability in Method Comparison Studies, and the Coefficient of Repeatability
Adjacent Analyses to Method Comparison Studies
Adjacent Analyses to Method Comparison Studies
Bland Altman Plot
Creating a Bland-Altman Plot from First Principles with R
Time Series With R - Part 1
Introduction to Time Series with R
Regression of Pairwise Differences and Sums
Regression of Pairwise Differences and Sums
Bland Altman Plot Ellipse
Proposal of an addition of an ellipse to the Bland-Altman plot
Limits of Agreement on Bland-Altman Plots
Enhancement of Bland-Altman Plots proposed by Bland-Altman 1986
Publication History of Bland-Altman (1986)
"Statistical methods for assessing agreement between two methods of clinical measurement. (Lancet 327, 307–310 (1986)" by Bland, J. M. & Altman, D. G. is one of the most cited papers of all time. This analysis tracks the citation history by since the paper's publication in the Lancet in 1986.
Technology Acceptance Model
Technology Acceptance Model
Working With Numbers
Working with Numbers and Integers
Matthews Correlation Coefficient
Matthews Correlation Coefficient
Cook's Distance
Assessing Model Fits with Cook's Distance
Deviance Residuals
Discussion about Deviance Residuals in GLMs
Air Quality Measurements
Air Quality Measurements
Air Passengers
The Air Passengers Dataset
Kaplan Meier Survival Models
Kaplan Meier Survival Models
The cheddar dataset
In a study of cheddar cheese from the LaTrobe Valley of Victoria, Australia, samples of cheese were analyzed for their chemical composition and were subjected to taste tests. Overall taste scores were obtained by combining the scores from several tasters.
Graphical Methods for Method Comparison
Graphical Methods for Method Comparison
K-Means Clustering with R
Introduction to K-Means Clustering with R
Run Length Encoding IDs with {data.table}
The rleid() function in the {data.table} R package
Interval Regression
Demonstration of Interval Regression using a worked example involving education data
Multinomial Logistic Regression
Multinomial Logistic Regression
Model Validation for Principal Component Analysis
Model Validation for Principal Component Analysis
Choosing the Number of PCA Components
Choosing the Number of PCA Components
Machine dataset - Variance-Covariance Matrices with {nlme}
Fitting Variance-Covaiance matrices to LME models
The {forcats} R package
Processing categorical data (factors) with the {forcats} R package
The {olsrr} R package
Deomstration of the {olsrr} R package
PCA - Wine Example
Demonstration of PCA on the Wine Dataset
One Hot Encoding
One Hot Encoding
Mean Imputation with R
Demonstration of Mean Imputation for Missing Values using a worked example with R
Advanced Regression Models
Extensions of the conventional OLS linear models
Akaike Information Criterion
Using the Akaike Information Criterion (AIC) for appraising linear model
R-Square Measures for Model Appraisal
Definitions of R-Square Measures for Model Appraisal for Linear Models
Huber Weighting for Robust Regression
Demonstration of Huber Weighting for Robust Regression
Shapiro-Wilk for Testing Normality
Testing the assumption of a normal disttributed data set.
Assessing Normality
Testing Normality in data to validate the required assumptions for inference procedures
Quasi-Poisson Regression
Quasi-Poisson Regression
Ceres Plots for Model Diagnostics
Implementation of ceres plots for model diagnostics using the ceresPlots() function in the {car} R pacakge
Introduction To Robust Regression
Introduction to Robust Regression
Robust Regression - Stackloss Example
Examining various Psi Operators for Robust Regression using the stackloss data set
Introduction To Truncated Regression
Introduction to Truncated Regression
Tobit Regression
Introduction to Tobit Regression
{inspectdf} R Package
inspectdf is collection of utilities for columnwise summary, comparison and visualisation of data frames.
{modelr} R Package
modelr is a package that helps you create elegant pipelines when modelling with the pipe operator in R. It provides functions for partitioning, resampling, model quality metrics, and interactions with models.
Nonlinearity in Linear Models
Nonlinearity in Linear Models
Influence Measures for Linear Models
Influence Measures for Linear Models
Linear Model Assumptions
Assumptions for Linear Models
Colinearity In Regression Models
Tests for Collinearity In Regression Models
Non Parametric Statistical Procedures with R
Non Parametric Statistical Procedures with R
The Monty Hall Problem
Using R to analyse the Monty Hall Problem
Zero-Inflated Poisson Regression
Zero-Inflated Poisson Regression
Cohen's Kappa
Implementation of Cohen's Kappa using the {vcd} R package
The {gvlma} R package
The {gvlma} package is a comprehensive, automatic testing suite for many of the assumptions of general linear models. It does both statistical tests and diagnostic plots using an extremely simple implementation for powerful results.
The {car} R package: Prestige Data Set Example
Demonstration of the {car} R package using the Prestige dataset as an example
The {broom} R package
The {broom} R package
Bartlett's test for Homogeneity of Variances
Bartlett's test for Homogeneity of Variances
Log Transformation
<Draft> Log Transformation of Data
Inference Procedures with R
Introduction to the main set of Inference Procedures used in R
Influence Measures for LME Models
Influence Measures for LME Models
Model Diagnostics - Definitions
Key definitions for Model Diagnostics
Most Dangerous Severe Weather Events
Storms and other severe weather events regularly cause public health disasters and economic hardships. These events often result in fatalities, injuries, and property damage. This analysis is a brief exploration of the U.S. National Oceanic and Atmospheric Administration's (NOAA) storm database. This database tracks when and where events occur along with estimated impacts.
Adding Smoothers to Scatterplots
Adding smoothed regression lines to ggplot scatterplots
Coursera Regression Quiz 4
Coursera Data Science Specialization - Quiz 4 for Regression Module
Diamonds Data Set
ggplot2 visualizations with the Diamonds Data set
Ordinal Logistic Regression
Implementing Ordinal Logistic Regression on the Student College Applications data set using the {polr} command from the {MASS} R package
Binomial Test
Implementation of the Binomial Test with R
Multinomial logistic regression with R
In statistics, multinomial logistic regression is a classification method that generalizes logistic regression to multiclass problems, i.e. with more than two possible discrete outcomes.
Correlation with R
Analysis of Correlation of two numeric variables with R
Chi-Square Test for Association
Using R to test the association of two categorical variables
Tests of Homogeneity of Variances
Using the Bartlett Test and Fligner Test to test the assumption of homogeneity of variances, as part of an overall ANOVA procedure.
Regression - Quiz 1
Quiz 1 for the Regression module as part of Coursera's Data Science Specialization
Likert Plots with gglikert
"gglikert()" generate a ggplot2 plot for a Likert 5-scale question
Negative Binomial Regression
Demonstration of Negative Binomial Regression using the "Days Absent" data set
Logistic Regression with the Pima Diabetes Dataset
Logistic Regression with the Pima Diabetes Dataset
CEL Data Set Visualization
Visualizations for the CEL data set
Miles Per Gallon Data Set
Visualizations for the mpg data set in ggplot2
Iteration using "repeat"
using "repeat" for iteration. The loop is broken with a break statement triggered by a logical condition
LME models for the Machines Data Set
Demonstration of LME model fitting for the Machines Data Set using the {nlme} R package
Orthodont Data set ( nlme R Package)
An exploration of the Orthodont data set, using models fitted by the {nlme} R package
Benford's Law
Demonstration of Benfords Distribution using {VGAM}
Outlier Detection with Mahalanobis Distances
Outlier Detection with Mahalanobis Distances
Lomax Distribution
Using R and the {Renext} R pacakge to work with the Lomax Distribution (also known as the Pareto Type 2 Distribution)
Weibull Distribution
Probability Distributions with R - The Weibull Distribution
System Date and Time
System Date and Time
Kolmogorov-Smirnov Test
Implementation of the Kolmogorov-Smirnov Test using R
Wilcoxon Test
Implementation of the Wilcoxon Test using R
Friedman Rank Sum Test
Implementation of the Friedman Test using the Warpbreaks data set
Fast Food Data Visualization - Version 1
Exercise for the Visualizing Data in the Tidyverse module - as part of the Coursera Tidyverse Specialization
Cluster Plots
Making Cluster plots with "geom_encircle()" from the {ggalt} R pacakge
Highcharter Series Plots
Plotting time series data with the {highcharter} R package
Using {GGally} R Package
Using the ggpairs() and ggscatmat() functions from the {GGally} R package to visualize bivariate data
Conover-Iman Test
The Conover-Iman test is a post hoc test that perform pairwise comparisons using the same rankings used in the Kruskal-Wallis test
Kruskal-Wallis Test with R
How to perform the Kruskal Wallis Test in R
Silhouette Plots
Making Silhouette plots with the {DataVisualization} R package
Weighting Methods for Robust Regression
Comparison of Weighting Methods for Robust Regression using R.
Roseplots
Making roseplots with {ggplot2}
Correlation Plots
Demonstration on how to create Correlation Plots using the ggcorrplot R package.
Making treemaps
making treemaps with the treemapify R package
Mahalanobis Distance
The Mahalanobis distance is the distance between a data point and the origin (mean) in a multivariate space, and is often used to identify outliers in multivariate statistical analyses.
mosaicMiss
Mosaic plot with information about missing/imputed values
Waterfall Plots
Using R to make waterfall plots
Making Sankey Plots with R and networkD3
Demonstration on making interactive Sankey plots with R and networkD3.This post is an amalgam of various gists and solutions on Stack Exchange.
Exploration of the trelliscopejs R package
The output is interactive and can not be run in R markdown
Inference Procedures With R - Worked Example
A demonstration on how to use R for an exercise from a Royal Statistical Society examination paper (Module 3 2011 Question 3)
Inference Procedures With R - Worked Example
A demonstration on how to use R for an exercise from a Royal Statistical Society examination paper (Module 3 2011 Question 1)
Iteration using cross2
An alternative to nested loops using the "cross2()" function trom the {purrr} pacakge
Toothgrowth Data
Statistical Analysis of Toothgrowth data set. This is the second part of project work for the Statistical Inference module for Coursera's Data Science Specialization
Truncated Regression
Truncated regression is used to model dependent variables for which some of the observations are not included in the analysis because of the value of the dependent variable.
Resampling with tidymodels
Resampling with tidymodels
tidymodels exercise
Using {tidymodels} with the NYCflights13 data
Diagnostics for LMEs with R
The R package {influence.ME} allows you to compute measures of influential data for mixed effects models generated by {lme4}.
R User Community Linkedin Followers
Growth in followership of variousR User Community language company pages on LinkedIn
Data Science Linkedin Followers
Growth in followership of various Data Science language company pages on LinkedIn
Julia Community Linkedin Followers
Growth in followership of various Julia programming language company pages on LinkedIn
Kaplan-Meier Analysis on Ovarian Cancer Data
Worked Example of a CS2B R programming actuarial exam question, featuring Survival Analysis
Wrangling Data in the Tidyverse - Course Project
Homework exercise for the "Wrangling Data in the Tidyverse Project" module in the Tidyverse Skills for Data Science in R Specialization
Importing Data into R Project
Homework exercise for the "Importing Data into R Project" module in the Tidyverse Skills for Data Science in R Specialization
Exponential Distribution
Worked Example of a CS1B R programming actuarial exam question, featuring the Exponential Distribution
Leverage
In statistics, leverage is a term used in connection with regression analysis and, in particular, in analyses aimed at identifying those observations that are far away from corresponding average predictor values.
Cook's Distance for Linear Models
A look at Cook's Distance for appraising and identifying influential observation in linear models in R.
Differences Between Dataframes
Demonstration on how to create a dataframe that comprises differences between two snapshot data frames, i.e. dataframes of identical construction, but containing information at different timepoints
Actuarial Exams -Worked Example
Worked Example of a CS2B R programming actuarial exam question, featuring simulated Claim values
Mortality Investigation Analysis
Worked Example of a CS2B R programming actuarial exam question, featuring Mortality Investigation Analysis
K-Means Cluster Analysis
Worked Example of a CS2B R programming actuarial exam question, featuring K-Means Cluster Analysis
Cox Proportion Hazard Regression - Part 1
Worked Example of a CS2B R programming actuarial exam question, featuring Cox Regression
Poisson Distribution - Dispersion Parameter
An examination of the Dispersion Parameter, which informs on which approach to use when modelling count variables.
Poisson Regression - Crabs Data Set
Poisson Regression example using the crabs data set (from the {glm2} R pacakge. This data set is derived from Agresti (2007, Table 3.2, pp.76-77). It gives 4 variables for each of 173 female horseshoe crabs.
Compound Distribution - Simulation Example
Worked Example of a CS2B R programming actuarial exam question, featuring the simulation of a compound probability distribution
Time Series Analysis - Air Passengers
Worked Example from the CS2B R programming actuarial examination. This is a time series analysis example using the Air Passengers data set.
Time-variant Transition Matrices
Worked example of CS2B R programming actuarial exam question
Lognormal Distribution - Worked Example
Worked Example of an exercise on a CS1B R programming exam paper
Measures Of Influences
Using DFFITS, DFBETA and PRESS to determine influential observations in a fitted linear model
Model Diagnostics - Testing for Homoscedasticity
Demonstration of how to perform the test for homoscedasticity of residuals of a linear model using the {car} R package
Durbin-Watson Test for Autocorrelation
Demonstration of how to perform the Durbin-Watson test for a linear model using the {car} R package
Demonstration of Patchwork R package
Demonstration of Patchwork R package. This is course material for the "Visualizing Data in the Tidyverse" which is part of the "Tidyverse Skills for Data Science in R Specialization"
Diagnostics Plots For Regression Analysis
Demonstration of how to create simple model diagnostic plots using in-built function in R
Tobit Regression
Demonstration of Tobit Regression
Model diagnostic tools with car R package
Demonstration of the functions offered by the car R package for model diagnostics. Here the R package is used to assess linear models fitted on the prestige dataset.
Sequencing and Run-length Encoding
Various options for sequence indices for data frames
Reproducible Research Project
Working with a subset of a United States medical expenditures dataset with information on costs for different medical conditions and in different areas of the country.
Testing Equality of Variance
Using the "var.test()" function in R to assess the validity of statistical assumptions in inference procedures
Measures of Dispersion
Demonstration of the intuition of Variance and Standard Deviation as measures of dispersion in statistics
Grubb's Test for Outliers
Implementation of the Grubbs' Test for Outliers in a univariate data set using R.
School Admissions
Using logistic regression to predict university admission.
Boxplots and Violinplots
Using {ggplot2} to assess the distributions of univariate data, comparing across categories
ggmosaic
Demonstration of ggmosaic R package for visualizing categorical data
Deming Regression
A demonstration of Deming Regression, an interesting alternative to OLS regression models that has applications in Method Comparison Studies
Creating Sunburst Plots with Plotly
This approach require a bespoke function that transforms a dataframe into a suitable hierarchical data structure
Exploratory Data Analysis - Assignment 1
Cousera's Data Science Specialization
Data Visualization in R with ggplot2 - Assignment 1
Data Visualization in R with ggplot2 - Assignment 1
Testing Normality With R
Draft One
Dice Roll Experiment
Draft 1