Numbers, numbers and more numbers. A statistician is a math expert who uses huge amounts of data to figure out how likely it is that something will happen, like your chances of winning the lottery.
See the word statistics in statistician? A statistician is an expert in the field of statistics, something you hear or see every day — the percentage of Americans who have cell phones, or how likely you are to be fit and healthy if you live in Oregon are statistics. The people who figure these things out are statisticians.