Render Google Maps Tiles with Mapnik and Python

If you want to take a bunch of GIS data and rasterize it as a tiled image map for public consumption, the folks at ESRI would be happy to sell you an expensive solution. Of course, as with oh-so-many projects, you can accomplish the same thing for free with open-source software. In this case, we'll use Python and a library called Mapnik to render beautiful map layers, then display them on Google Maps, just like this demo rendering of my home county!

Ready to get started? Dust off your Python skills, and let's go!

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Project Mean Customer Lifetime by Modeling Churn

In a past post on analyzing churn in the subscription or Software as a Service business, I talked about two different ways to quantify the dollar cost of churn. You could use 1 / churn as an estimation of mean customer lifetime (though this simple method makes a lot of assumptions). Or, you could use “pseudo-observations” to calculate the dollar value of certain groups of customers during a particular time period (which doesn’t let you quantify the full lifetime value of a customer).

But what if there was another way? What if we took our Kaplan-Meier best estimate of our churn curve, fit a linear model to that model, and then projected it out?

Inception Squint

A model within a model, if you will. Churnception.

Well, as it turns out, we’d get a reasonable estimation of our lifetime churn curve, which would let us estimate average customer lifetime, and customer lifetime value. Let’s get started.

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Identifying Trends in SQL with Linear Regression

One of the best ways to learn how a statistical model really works is to code the underlying math for it yourself. Today, we’re going to do that with simple linear regression.

Data Smart Cover

In the book Data Smart, John Foreman introduces a bunch of awesome methodologies by walking you through how to build them in Excel…

Of course, doing regression in SQL also has (some) practical use as well! For example, suppose you wanted to identify which city in a database of temperature records had the biggest warming trend in the last month. This method would send you on your way without having to bring your data into an external tool. Nifty!

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Send Google Analytics Data to Your Own Server

In last week’s post, we explored how to tag individual users and hits with unique identifiers in Google Analytics, so that an analyst could export raw data from the Google Analytics API for complex statistical analyses not possible in the GA interface. But there are undoubtedly some situations in which even that solution isn’t good enough – Google limits the number of metrics and dimensions you can download in a single query, for example. What do you do then?

Luckily, there’s a solution for this. We’ll just send Google Analytics data on a little detour from the user’s browser to our own web server, process it ourselves, and query to our hearts content!

The 1945 movie, Detour, starring Tom Neal and Ann Savage.

The methodology I’ll summarize today allows an organization to leverage much of the value-add of Google Analytics (for instance, they’ve already done all the hard work of detecting JavaScript, flash, screen size, page, URL, etc.) while still processing the data on their own servers. It’s a massive win-win.

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Export Raw Data from Google Analytics (the Free Way)

Today, we’re going to use a couple of lines of JavaScript code to get free access to raw data from Google Analytics. That’s a feature that’s usually only available in Google Analytics Premium, a product which will set you back a cool $150,000 a year.

In this how-to video, the author merges customer data with Google Analytics data via Google BigQuery. Luckily, you can unlock these kinds of features without having to take out a second mortgage.

Think that sounds like a cool idea? Let’s get started.

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Random Forest Classifiers as a Web Service in PHP

Recently, I found myself wanting to be able to make real-time, online predictions using a random forest classifier trained in R. Of course, there are many ways to make that happen – I could have used yhat’s ScienceOps product, for example. But, for project-specific reasons, I decided that the best route to go in this case was to get my hands dirty and build my own RESTful API for making predictions using my model.

Apparently, back in 2011, Disney debuted a show called "So Random." Thankfully, it only ran for a single season...

Apparently, back in 2011, Disney debuted a show called “So Random.” Thankfully, it only ran for a single season…

In this post, we’ll walk through all of the code necessary to export a random forest classifier from R and use it to make real-time online predictions in a PHP script.

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Probabilities in Google Analytics Content Experiments

Have you ever taken a look at the “probability of outperforming” metric in Google Analytics’ Content Experiments and wondered how it was calculated? Have you ever scratched your head because the numbers didn’t make sense to you? I certainly have. It’s hard to see experiment results like the ones depicted below and not wonder what’s going on underneath the hood.

GA Experiment Data

Real data from a GA content experiment, showing an under-performing variant with a >50% chance of outperforming the original. It’s like trash-talking when you’re down at the half.

In this post, we’ll highlight how Google’s Content Experiments work, why it’s a really smart idea, and why you might still want to do a little bit of the heavy lifting yourself…

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Are Your Affiliate Partners Cannibalizing Organic Sales?

What if your business was paying a bunch of extra money to bring in sales that would have happened anyway?

In the e-commerce business, affiliate marketing promises to deliver increased sales by getting your name and products showing up on dozens of sites, blogs, and social media pages. Of course, this sounds like a great boon – more traffic, more sales, more profits. But, in many cases, the results aren’t nearly as good as you might expect. If you’re not careful, your affiliate program can cannibalize sales that were going to happen anyway…

Cutco knives seem like the 1990's equivalent of affiliate marketing...Image Credit: Hustvedt  [CC BY-SA 3.0 or GFDL], on Wikimedia Commons)

Cutco knives – affiliate marketing’s evil twin brother.
(Image Credit: Hustvedt [CC BY-SA 3.0 or GFDL], on Wikimedia Commons)

In today’s post, I’ll show you a simple technique to figure out how cannibalistic your affiliate program is, using a specially-designed Google Analytics segment.

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Cell Suppression in SAS – Final Thoughts

Over the last several weeks, I’ve blogged about two different methods for solving the small cell suppression problem using SAS Macro code. In the first, we used a heuristic approach to find a solution that was workable but not necessarily optimal. In the second, we solved the problem to proven optimality with SAS PROC OPTMODEL. But all of this leaves a few open questions…

For example, how much better is the optimal approach than the heuristic? Is there ever a reason not to prefer the optimal approach? And what are some other improvements and techniques that a researcher using these macros might want to know about? I’ll spend this post reflecting on our two solutions and covering a few of these bases.

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Optimal Cell Suppression in SAS – Final Macro

In last week’s post, we constructed a set of constraints to bound a binary integer program for solving the small cell suppression problem. These constraints allow us to ensure that every group of data points which could be aggregated across in a tabular report contains either 0 or 2+ suppressed cells.

Cop-out test answer.

At some point before age five, every kid masters the art of satisfying constraints with solutions that are hilariously non-optimal.

Obviously, there’s plenty of ways we could satisfy our constraints – suppressing everything, for example. But we want choose the optimal pattern of secondarily suppressed cells to minimize data loss. So, we’re going to tackle the problem using binary integer programming in PROC OPTMODEL. Strap yourself in, folks – it’s going to be an exciting ride.

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