Google Analytics is not providing all the keyword traffic information anymore. The most trafficked keyword now is usually “not provided”. If this segment is not too big the accuracy of the organic keyword report is still reasonable. Especially if we assume the “not provided” segment is more or less distributed among many keywords.
However if we want to track a keyword’s traffic over time we have a problem.
For example we may want to compare keyword traffic for “keyword 1” from this August as compared to last August when “not provided” didn’t exist. It is hard to know how accurate our comparison is.
As time goes on this segment may increase in size which means these kinds of comparisons will always be inaccurate. If this information is important you may need to use an alternative analytics package which provides more complete information.
So if you see that traffic for a keyword is trending down compared to last year—don’t panic. Many of the searches may be hidden in the “not provided” segment. However if there is a big difference you may want to go ahead and panic.