Assuming a sufficiently large set of data, is there a formula for "predicting" a mean value with a certain degree of accuracy without calculating the mean for the whole set of data?
Example, say I have a million data points of whole numbers between 100 and 900. Is there a way to predict the mean +- 5 points with a smaller subset of the data (say 10,000 data points)?
I'm a sw dev not a stats person, but have been asked to report on a rough average, and our existing tools are having trouble with processing the whole data set.
Edit: By tooling, I'm referring to our cassandra DB where the data is stored. I do not have the ability to install Spark or another analytics platform, and the inbuilt aggregation queries are failing with data sets much smaller than 1 million records.