It's easy to understand that different people respond to different colors, images, messages, and ultimately products. Sometimes a well presented, visually appealing ad does very poorly in terms of actual conversions, and sometimes the conversion rate can increase by 50% or more just by changing a few colors.

Once the marketing campaign's goal has been established, there needs to be a method to determine if the goal was achieved. Using Google Analytics or Omniture to set goals for your website is a great place to start. If the goal of your website is to get somebody to register, then you can set the Thank You page as your goal page.  Any time this page is accessed, it's counted in your analytics software. In addition, a funnel can be set up so that you can track where people are abandoning the site before the goal is established. In an E-Commerce site, perhaps people are leaving on the billing info or product upsell step. Knowing this, the page could be redesigned to make it easier to navigate, which will lead to more conversions.

Once the baseline conversion rates are established, you can start testing different colors, copy, and images to see how that affects the overall conversion rate. In other words, do more people make it from page A to page B.

For simple tests, just watching the Analytics goal metrics can be good enough; For example, if the current conversion rate is 3% for August and it increases to 4% after all of the buttons are changed from blue to green, it's easy to see that people respond better to the new color.  It's rarely this simple though.  Pages change, new ones are added, people may respond differently at different times of the year.

This is where AB testing or MVT (multi-variant testing) comes in. This allows you to show different pages to different people at the same time. In AB testing, there are 2 options, and MVT may have many variations.

A free, but somewhat messy option is Google Optimizer. This requires that you know a little about JavaScript. The way it works is that you add some JavaScript code to your web page. Then in the Optimizer interface, you specify the different options to be displayed and it tracks which option gets better results based on your goal such as the number of times people click on "Buy Now". Because it requires that you add JS code to your pages, you'll need a very good content management system to keep track of it all.

My Market Toolkit is one of the best options because of the way the template system works. The template is split up into smaller blocks, which makes it easy to manage and keep different parts of the website organized. This way, Optimizer's JS code could be segmented away from the rest of the HTML so that it's easy to remove once the test is done.

By using statistics to determine how well your marketing campaigns are performing, your marketing budget will give you the best ROI possible.