Build and Evaluate A Logistic Regression Classifier
Written by Matt Dancho
This article is part of a R-Tips Weekly, a weekly video tutorial that shows you step-by-step how to do common R coding tasks.
Logistic regression is a simple, yet powerful classification model. In this tutorial, learn how to build a predictive classifier that classifies the age of a vehicle. Then use
ggplot to tell the story!
Here are the links to get set up. 👇
In this analysis we learn that newer vehicles are MORE EFFICIENT, and we’ll make a data visualization that tells the story.
How did we make this plot?
- Our logistic regression classifier modeled the data
- We used
VIPto find the most important features
- We visualized with ggplot 💥
Making a Logistic Regression Classifier
Logistic regression is a must-know tool in your data science arsenal.
- Logistic Regression is easy to explain
- The classifier has no tuning parameters (no knobs that need adjusted)
Simply split our dataset, train on the training set, evaluate on the testing set.
Folks, it’s that simple. 👏
Evaluating Our Classification Model
Question: How do we know our if our model is good?
Answer: Area Under the Curve (AUC)!
- Simple measure.
- We want greater than 0.5.
- Closer to 1.0, the better our model is.
- Bonus: ROC Plot - A way to visualize the AUC.
Telling the Story
What can we do with a Logistic Regression Classifier? Let’s develop a story to communicate our insight!
1. First, find the most important features (predictors) using
2. Next, use
ggplot() to make a visualization that focuses on the top features:
- HWY: The highway fuel economy (miles per gallon)
- CLASS: The Vehicle Class (e.g. pickup, subcompact, SUV)
What did we learn using Logistic Regression?
It’s clear now:
- Vehicles have become more efficient over time.
- Highway fuel economy has gone up for every single class of vehicle.
Your story-telling skills are amazing. Santa approves. 👇
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