Why is going throwing my site around?

Ive been ranked in the top 10 of google for about 3 months now for a keyword which I have been constantly been working on up to about a month ago, now everyday it is in a different position for this keyword, why is google throwing it around so much?? 3rd on monday, 7th on tuesday, 5th on wednesday, 4th on thursday and today 3rd this morning now 5th!!! why isnt it staying in one position and updating once a week??

 

how old is the domain name ??

 

It seems google is doing some updates. At least you're still in the top 10 while this happens...

 

The domain is 4 years old, and Ive made sure that only white hat seo work has been done on it

 

Different datacenters is my guess.

 

May it be something to do with how often im getting cached??? its every 3 days.

 

i think it's maybe just because google keep trying new their algos? normally old sites result should not been moved that much. this is only on one keywords or all keywords?

 

Ive seen this in some of my sites, it seems they are updating the serps