Regression

A Visual Description of Multicollinearity

Multicollinearity is one of those terms in statistics that is often defined in one of two ways:

1. Very mathematical terms that make no sense — I mean, what is a linear combination anyway?

2. Completely oversimplified in order to avoid the mathematical terms — it’s a high correlation, right?

So what is it really? In English?

R-Squared for Mixed Effects Models

When learning about linear models —that is, regression, ANOVA, and similar techniques—we are taught to calculate an R². The R² has the following useful properties:

The range is limited to [0,1], so we can easily judge how relatively large it is.
It is standardized, meaning its value does not depend on the scale of the variables involved in the analysis.
The interpretation is pretty clear: It is the proportion of variability in the outcome that can be explained by the independent variables in the model.

The calculation of the R² is also intuitive, once you understand the concepts of variance and prediction. [Read more…] about R-Squared for Mixed Effects Models

Member Training: Elements of Experimental Design

by Karen Grace-Martin

Whether or not you run experiments, there are elements of experimental design that affect how you need to analyze many types of studies.

The most fundamental of these are replication, randomization, and blocking. These key design elements come up in studies under all sorts of names: trials, replicates, multi-level nesting, repeated measures. Any data set that requires mixed or multilevel models has some of these design elements. [Read more…] about Member Training: Elements of Experimental Design

Member Training: A Predictive Modeling Primer: Regression and Beyond

by guest

Predicting future outcomes, the next steps in a process, or the best choice(s) from an array of possibilities are all essential needs in many fields. The predictive model is used as a decision making tool in advertising and marketing, meteorology, economics, insurance, health care, engineering, and would probably be useful in your work too! [Read more…] about Member Training: A Predictive Modeling Primer: Regression and Beyond

Statistical Models for Truncated and Censored Data

by Jeff Meyer Leave a Comment

by Jeff Meyer

As mentioned in a previous post, there is a significant difference between truncated and censored data.

Truncated data eliminates observations from an analysis based on a maximum and/or minimum value for a variable.

Censored data has limits on the maximum and/or minimum value for a variable but includes all observations in the analysis.

As a result, the models for analysis of these data are different. [Read more…] about Statistical Models for Truncated and Censored Data

The Four Stages of Mastering Statistical Analysis

by Karen Grace-Martin 3 Comments

At The Analysis Factor, we are on a mission to help researchers improve their statistical skills so they can do amazing research.

We all tend to think of “Statistical Analysis” as one big skill, but it’s not.

Over the years of training, coaching, and mentoring data analysts at all stages, I’ve realized there are four fundamental stages of statistical skill:

Stage 1: The Fundamentals

Stage 2: Linear Models

Stage 3: Extensions of Linear Models

Stage 4: Advanced Models

There is also a stage beyond these where the mathematical statisticians dwell. But that stage is required for such a tiny fraction of data analysis projects, we’re going to ignore that one for now.

If you try to master the skill of “statistical analysis” as a whole, it’s going to be overwhelming.

And honestly, you’ll never finish. It’s too big of a field.

But if you can work through these stages, you’ll find you can learn and do just about any statistical analysis you need to. [Read more…] about The Four Stages of Mastering Statistical Analysis