The beginning of each SEO project should deal with the question of what keywords a website should be optimized. SEO campaigns can only focus on a limited number of keywords. Therefore it is so important to make an informed keyword selection, which means that predicting traffic numbers is going to play a key role in your selection.
If you are optimizing your website correctly then in many cases with you are going to be dealing an enormous amount of keywords. A manual keyword selection is virtually impossible without something to help you narrow the field. Picking targeted keywords is good, but if they are unlikely to be searched for in the next twelve months then what is the point?
This is probably the first Google tool that people think of when they consider forecasting their traffic numbers. If you index the information you get from Google insights over a 12-month period, you will find that it is fairly accurate in predicting the traffic attracted by certain keywords. The data you mine with this tool should be used as a guide, because no forecasting technology is ever able to be 100% accurate all the time. If you pick fairly generic and popular keywords then the tool may do some of the forecasting for you, where the forecasted traffic numbers appear as a broken line on the graphs.
Google Adwords Keywords Tool
The monthly search data function has been removed from this tool. This is possibly because the monthly statistics always seemed to be marred by inaccuracy. The possible reason for this is because it judges how much a keyword will be used in a week, or a day, and multiplies it over 30 days to generate a monthly estimate. This means that statistically the monthly data will probably be wrong more times than it will be right. Still if you would like to see which keywords are long-tailed and rarely searched then this is a very good tool.
This is a frighteningly good tool that gives away some very detailed information. It is puzzling why Google do not charge for the use of such a powerful tool. The only possible criticism of this tool is that it always seems to err on the side of caution, and gives very conservative data. There are times when you can draw more traffic with your keywords than this tool is willing to admit.
The folly of forecasting
You must consider various factors in the relevant keyword selection, such as search volume, the strength of the site, the importance of a keyword for the company, individually weighted and chained together. There is another angle however, which makes the process of forecasting so difficult that your forecasts may as well be random predictions. This exterior force is your competition. You have no idea what your competition are going to optimize their websites for. You also have no idea where they are going to get their forecasting information from. If your competitors are using the same forecasting tools and resources as you then does that not suggest that they will come to the same conclusions as you? Every time you use a forecast to create your keyword group, are you not pitting yourself against your competitors in an even more precarious way?
Applying your forecasted keywords to your website is going to have varied outcomes