Yes, I notice this quite a bit as well. I honestly cannot find a reasonable answer to this question. I notice that it usually happens to keywords with monthly search volumes of a few thousand or less, but cannot pinpoint anything else that seems to trigger the 'Insufficient Data' result. It happens even more frequently when you get into search volumes lower than about 200. With search volumes this low, it is hard to say how accurate any of this data really is.
On a similar note, I tend not to use the "Approx Search Volume" for the previous month statistic. Instead of going by the search volume for the previous month, I use the “Average Search Volume” number in addition to the "Search Volume Trends" graph, which is an optional column to display. This is a small bar graph (shown below) that will give you a general idea of the monthly trends for this keyword. You can see which months are stronger than others as well as any recent drops in search volume.
Yes, I notice this as well
Yes, I notice this quite a bit as well. I honestly cannot find a reasonable answer to this question. I notice that it usually happens to keywords with monthly search volumes of a few thousand or less, but cannot pinpoint anything else that seems to trigger the 'Insufficient Data' result. It happens even more frequently when you get into search volumes lower than about 200. With search volumes this low, it is hard to say how accurate any of this data really is.
On a similar note, I tend not to use the "Approx Search Volume" for the previous month statistic. Instead of going by the search volume for the previous month, I use the “Average Search Volume” number in addition to the "Search Volume Trends" graph, which is an optional column to display. This is a small bar graph (shown below) that will give you a general idea of the monthly trends for this keyword. You can see which months are stronger than others as well as any recent drops in search volume.