Sunday 24 June 2007

Basic Metrics

-Akshay Ranganath

Now that we've see what analytics is and how to start analytics, let's get on to the next stage – seeing the metrics.

At this point, the assumption is that you have a site to analyze and the analytics code has been pasted onto each and every page that you want to be tracked via the analytics software. Like I explained before our blog is using Google Analytics. Hence, I'll be showing the screen dumps from the Google Analytics site.

What metrics to see?
This is a very good question! The metrics that you would be interested to see will generally depend on what you intend to measure in the first place. Generally though, there is a basic set of metrics that needs to be captured for any higher level of analysis to take place. In this article, I'll be covering these simple and general metrics.
For sake of clarity and better understanding, I'll be defining the various metrics, as defined in Google Analytics glossary (1) and the Omniture SiteCatalyst (2) help center. This is just to give you a glimpse on the little differences that vendors may sometime have in the way their metrics work.

So, let's get on with exploring the metrics.

Hit

Hit is a metric that is more of a remnant of the log-file based era. Basically, it was a measure of number of times any resource was served from a web server. For example, if your page has a logo, a stylesheet file and the actual HTML, one hit would be reported for each of the file – in effect when this page loaded, the site would record three hits.
Since this measure is not of much use, it is not reported on most of the modern tools.

Definitions

SiteCatalyst: A request to the web server for a file. This can be an HTML page, an image (jpeg, gif, png, etc.), a sound clip, a cgi script, and many other file types. An HTML page can account for several hits: the page itself, each image on the page, and any embedded sound or video clips. Therefore, the number of hits a website receives is not a valid popularity gauge, but rather is an indication of server use and loading.

Google Analytics: A single entry in a server log file, generated when a user requests a resource on a website; a request can result in an error or a successful transmission of any data type.

PageView

Page view is the next higher order metric. This measures the number of times a particular page having the analytics code is loaded by the browser. So, if the same page mentioned above were loaded, the analytics code would be present in the HTML page and hence, only one pageview would be noted by the analytics program.

This is the most basic metric that is measured by most of the analytics packages.

Definitions

SiteCatalyst: A request for a full-page document (rather than an element of a page such as an image, movie, or audio file) on a website; hits are not a useful comparison between websites or parts of the same website, since each webpage is made up of an arbitrary number of individual files

Google Analytics: A pageview is an instance of a page being loaded by a browser.

How to see?
On the Google Analytics do the following to see the PageView report:
Visitors > Visitor Trending > Pageviews



Visit / Session

A session or a visit is the interaction of a user with the web site. If I access a site, close the site, access something else and then return back to the site, then, I've visited the site twice. If I access a site and leave it idle for a specific period of time and then try again, then, it is considered a new visit or a session.

This type of a definition is necessary since the session or visit is based on cookies. A concept of session is needed to form a base of an interaction from which any meaning can be derived. For example, if you go to a shop, visit once and then return again to exchange some article, for the shop, you've visited twice. Based on this, they can form some information like you came to the shop twice, but bought only once. Or some data like, you came to the shop, stayed for about 30 minutes and then made a purchase of $ 100.

Of course, there is caveat in terms of the visit from a computer. Since it is based on cookies, if you clear the cookies in the middle of an interaction or if the site is accessed by your friend when you left for a quick break – such details cannot be captured.

Definitions

SiteCatalyst: A visit is a term that refers to a visitor’s access to a website. The visit begins when a person first views a page on your company's website. It will continue until that person stops all activity on the site for 30 minutes. For example, if you log in to www.omniture.com, you have one instance of a visit that will last until you have incurred 30 minutes of inactivity, i.e. you have closed the browser or left your computer. If you are inactive for more than 30 minutes, and then you log on again, it is considered a new visit. SiteCatalyst also terminates a visit after 12 hours of continuous activity.

Google Analytics: A period of interaction between a visitor's browser and a particular website, ending when the browser is closed or shut down, or when the user has been inactive on that site for a specified period of time.
For the purpose of Google Analytics reports, a session is considered to have ended if the user has been inactive on the site for 30 minutes.

How to see?
Visitors > Visitor Trending > Visits



Visitor

In the simplest terms, a Visit is performed by a visitor. This is the level where we are trying to associate an human actor in the entire process of interaction.

SiteCatalyst: A Visitor is a construct designed to come as close as possible to defining the number of actual, distinct people who visited a website. There is of course no way to know if two people are sharing a computer from the website's perspective, but a good visitor-tracking system can come close to the actual number. The most accurate visitor-tracking systems generally employ cookies to maintain tallies of distinct visitors.

Google Analytics
: The number of actual, distinct people who visited a website. Omniture employs cookies to maintain tallies of distinct visitors.

How to see?
Just click on the Visitors option on the left hand menu.



Summary
Trying to co-relate whatever we've learnt till now with an example:
If I were to go to Amazon.com and view some book article, probably add a few things to my cart, edit or remove items and then check out and close the site, I am the visitor who generated so many page views, one each for all the pages that I saw. If I did all the activities without closing my browser and without leaving my browser idle for more than 30 minutes of a time, I've done the entire job in one visit!

This covers a short chapter on the absolute very basic metrics of any analytics package.

In the subsequent chapters, I'll be examining how the metrics can be used to derive various other details for a site.

References:
1. Google Analytics Glossary
2. Omniture SiteCatalyst Help.

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