Accurate Analytics Require Cookies

  |  March 5, 2004   |  Comments

Effectively track site visitors for accurate activity metrics.

Effectively tracking site visitors is extremely important for gathering accurate site-activity metrics. Over the last few years, cookies have gotten almost as bad a reputation as the more well-known chocolate chip variety (my personal favorite) have among the diet conscious. The former has a reputation for invading privacy; the latter for expanding waistlines.

Cookies can be a good thing, especially when fresh out of the oven with a glass of cold milk. Or, when used properly, to better understand and service your customers.

Cookies define visitors and "sessionize" their data. These are two of the more important requirements for actionable Web analytics. You want to segment your visitors and identify their visits, from first page viewed to the last and all pages in between.

Define Tracking Setups

Let's review some options and preferred setups to track visitors and define sessions for your site.

Robert Volz, one of my partners and a strategic consultant explains:

To effectively track a visitor and her session we need a visitor-specific unique identifier that is maintained throughout the visit to the site. There are many accepted and effective methods to track and sessionize visitor activity. Some of the most common visitor identifiers are IP address, IP address and browser (user agent), authenticated user name, session cookies, and persistent cookies, to name a few. Once you identify the visitor, you then sessionize the activity using their unique identifier.

The most basic and common methods for tracking visit sessions are IP address, and IP address and user agent. They're used as a default for tracking sessions because an IP address is required to surf the Internet. Using cookies to track visitors and sessions is one of the best methods, but it's difficult to properly configure and implement. Though not the only methods, they're the most prevalent and can be used by almost all sites.

So let's further examine the two methods.

Tracking visitors via their IP addresses beats not tracking at all. But it's ineffective for unique identification or sessionization, as there are a limited number of IP addresses available. Volz clarifies:

You can think of each IP address as one room in a 4 billion room hotel where you or your customers stay whenever you access the Internet. This may seem like a lot, but many of the floors are reserved for special purposes, each site has a permanent room, and so there is limited rental space for Internet surfing. Since you only need space while you are actually interacting with the Internet (surfing), the rooms (IP addresses) are shared among many surfers (visitors). This sharing not only occurs after one visitor leaves (signs off the Internet), but while they are signed on and more often now while they are on a site -- they can switch rooms. All this sharing and changing of rooms (IP addresses) means that using an IP address as a visitor identifier is confusing to analyze.

Because the IP address is shared by visitors at different times, it appears you get many repeat visitors. Actually, they're different customers sharing one IP. Each customer is assigned a different IP address each time she surfs. That reduces the reported number of returning visitors.

IP addresses can also change while visitors surf. Instead of one visitor's click stream, analysis may reveal two visitors with entirely different behaviors. Another likely occurrence is many visitors look like one visitor because they access the Internet through a proxy server, such as Akamai or AOL. This is very common with both business-to-consumer (B2C) and business-to-business (B2B) sites.

The more traffic volume, the bigger the problem. Although analysis is compromised, results tend to trend consistently. It is possible to gain insight from traffic patterns and make changes to your site using visitor IP address as the visit identifier.

Cookie Identification

Cookies are small files given to site visitors. In many cases, they're saved on visitors' computers. Although the cookie has gotten some bad press and can be misused (as well as misunderstood), many cookies are very good for customers. They improve their Web experience through personalization and optimization.

The best cookie is a first-party, persistent, non-personal, P3P-compliant tracking cookie. Most of the Internet community accepts it. Most visitors don't delete their cookies very often, and almost never do so during a browsing session. As a result, you can use these cookies as visitor identifiers and establish a proper method for tracking visitors and their sessions.

Volz explains:

We establish the cookie as a unique identifier for each visitor to the site, and, when properly configured, [it] remains with the visitor until they either remove the cookie or the cookie expires. There is still some cookie sharing, but only by visitors [who] use the same computer and log in to surf the Internet (for example, through Internet kiosks). Unless your site is accessed heavily from kiosk visitors, tracking with cookies is an exceptionally effective method for getting good base visitor identification and sessionization for use throughout your analysis.

Types of cookies:

  • Persistent or session

  • First party or third party

  • Non-personal or personal

  • P3P compliant or not

Persistent or Session

A persistent cookie is saved to the computer and remains for a specified period. A session cookie isn't saved to the computer and expires at the end of the visitor's stay. Both can track pages visited and individual visits. Only the persistent cookie tracks repeat visitors.

First Party or Third Party

A first-party cookie is served from the visited site (e.g., A third-party cookie is served from outside your site (e.g., Third-party cookies are often served by outside tracking vendors and Web analytics services.

The primary difference is first-party cookies are mostly accepted by default browser settings, while third-party cookies are blocked.

Non-Personal or Personal

If you want to track visitors and their sessions, don't set cookies to acquire personal information. If you do need personalized cookies, consider implementing multiple cookies. This way, each cookie can be configured for a specific task.

P3P Compliant?

Volz explains P3P-compliance information in cookies:

If you are compliant, then include it since it also means that more visitors will accept your cookie. But if your cookie is first party and non-personal, then it is accepted almost 99 percent of the time, so this may not be needed.

Optimizing Only Works With Proper Tracking

One of the basic requirements for good analytic metrics is effective tracking. Using the best session identifier available provides a foundation to:

  • Understand your customers

  • Understand their surfing habits

  • Know how often they return

  • Get the best analysis possible

Implementing persistent, first-party, non-personal cookies is one of the best ways to track site activity and sessionize data. Instead of tracking visits by IP address, track with cookies. This increases accuracy and comprehension of your Web analytics.

For more details, read "Web Analytics Demystified" by Eric Peterson, former WebSideStory employee, now a Jupiter Research analyst. Meantime, I'll munch some chocolate chip cookies.


Bryan Eisenberg

Bryan Eisenberg is co-founder and chief marketing officer (CMO) of IdealSpot. He is co-author of the Wall Street Journal, Amazon, BusinessWeek, and New York Times best-selling books Call to Action, Waiting For Your Cat to Bark?, and Always Be Testing, and Buyer Legends. Bryan is a keynote speaker and has keynoted conferences globally such as Gultaggen,, Direct Marketing Association, MarketingSherpa, Econsultancy, Webcom, the Canadian Marketing Association, and others for the past 10 years. Bryan was named a winner of the Marketing Edge's Rising Stars Awards, recognized by eConsultancy members as one of the top 10 User Experience Gurus, selected as one of the inaugural iMedia Top 25 Marketers, and has been recognized as most influential in PPC, Social Selling, OmniChannel Retail. Bryan serves as an advisory board member of several venture capital backed companies such as Sightly, UserTesting, Monetate, ChatID, Nomi, and BazaarVoice. He works with his co-author and brother Jeffrey Eisenberg. You can find them at

COMMENTSCommenting policy

comments powered by Disqus

Get the ClickZ Analytics newsletter delivered to you. Subscribe today!



Featured White Papers

2015 Holiday Email Guide

2015 Holiday Email Guide
The holidays are just around the corner. Download this whitepaper to find out how to create successful holiday email campaigns that drive engagement and revenue.

Three Ways to Make Your Big Data More Valuable

Three Ways to Make Your Big Data More Valuable
Big data holds a lot of promise for marketers, but are marketers ready to make the most of it to drive better business decisions and improve ROI? This study looks at the hidden challenges modern marketers face when trying to put big data to use.