HCI – Tech Blog

Aggregated values on a Google Map

UPDATE 27/08/09: The functionalities of my version of MarkerClusterer have been included in the official Google code project, you can find it gmaps-utility-library-dev. The most interesting part was the so called MarkerClusterer.

Imagine you need to show thousands of markers on a map. There may be many reasons for doing so, for example temperature data, unemployment distributions, and the like. You want to have a precise view, hence the need for a marker in every town or borough. What Xiaoxi and other developed, is a marker able to group all the markers in a certain area. This is a MarkerClusterer. Your map gets split into clusters (of which you can specify the size – but hopefully more fine grained ways of defining areas will be made available) and you show for every cluster a single marker, which is labelled with the total count of markers in that cluster.

I thought that this opened a way to get something more precise and able to make reasoning over map data. Once you have a ClusterMarker, wouldn’t it be wonderful if you had the possibility of displaying some other data on it, rather than the simple count? For example, in the temperatures distribution case, I would be interested in seeing the average temperature of the cluster.

That’s why I developed this fork of the original class (but I’ve applied to get it into the main project – finger crossed!) that allows you to do what follows:

create a set of values to tag the locations (so that you technically attach a value to each marker)
define a function that is able to return an aggregate value upon the values you passed, automatically for each cluster

That’s all. The result is very simple, but I believe it is a good way to start thinking about how the visualization of distributed data may affect the usability of a map and the understanding of information it carries. Here’s a snapshot of the two versions, the old on the left (bearing just the count) and the new on the right (with average data). Data here refer to NHS Hospital Death Rates, as published on here. If you want to see the full map relating to this example, click here.

Wolfram Alpha and user experience

There are a lot of ongoing discussions about the power of Wolfram Alpha. I think that most of these conversations are flawed because of the argument that Wolfram Alpha does not find you enough information.

I believe that the mistake here lies in the common way the press have introduced the service. Wolfram himself has not been clear enough, and when he has, the press has of course misinterpreted him. Wolfram Alpha is not a search engine.

Many articles and blogs have been issued on the topic will Wolfram Alpha be the end of Google?
The problem here is that the two services are actually very different. Wolfram Alpha is a self-defined computational knowledge engine, not a search engine like Google. Google is able to return millions of results for a single search, whilst Alpha returns a single, often aggregated, result about some topic.

Alpha is basically an aggregator of information. It selects information from different data sources and presents them to the user in a nice and understandable way. Google is more like searching in the phone directory. So you’re supposed to ask different questions to the two services.

Of course, Alpha makes mistakes. A curious example I’ve found is the search for the keyword “Bologna”. Bologna is primarily the name of a town in Northern Italy (the one in which I attended university); it is also the name of a kind of ham, commonly known as “Mortadella”, especially outside Bologna itself. In Milan, for example, Mortadella is commonly called Bologna.

Well, search for Bologna on Google, and compare it with results on Alpha.

Google will return mostly pages about the town of Bologna, and its football team, where Alpha will tell you nutritional information of Mortadella.

Is this a ‘mistake’? I think that the only mistake is in the expectations users have about Alpha. it yields results from a structured knowledge base, hence its index is not as general as the one of Google. Nonetheless, I believe that there’s at least a problem in the user interface that should be corrected: the search box. It’s exactly the same as Google’s, same shape, same height, same width. But is there any alternative way of presenting an answering engine on the Internet?

What I think is that more HCI research is needed to let users understand what are the goals and the capabilities of a service like Alpha. If users think of it as a search engine, it will never have success.

Just to have a hint of what Alpha should be about, try this search.