When analyzing a page for a multi-word phrase, frequency by default will reflect only those occurrences where the words of the phrase all appear together in the page area. If on the Page Analyzer screen you disable exact match searching, then frequency will count occurrences of ANY of the words in the phrase that are found in the page area.
For Example:
"Computer programmers write the instructions that a computer reads."
If our keyword was computer programmers then the frequency above for an exact match would be one. A frequency of 1.5 would be returned if we were doing a non-exact match. That's because we count "Computer" as one match, "programmers" as another match, and "computer" again as a third match, then we divide by the number of words in the phrase to determine a non-exact match count.
In theory, when a search is made with surrounding quotes on a search engine, only words found together will be assigned relevance. In practice, search engines are often inconsistent in requiring keywords to appear together on exact match searches. Sometimes pages will be returned that include only some of the words in the phrase. In other cases, all of the words may be present but in different places on the page, even when an exact search was performed. Because of this, it's a good idea to analyze and optimize your page for non-exact searches as well.
Please beware the "Top Averages" feature if turned on will be calculated in relation to whether you are doing an exact or non-exact analysis. Therefore, you will see a different set of Top Average numbers depending on whether you check the Exact Match checkbox on the first tab of the Page Critic screen.