Standard deviation – The standard deviation is the measurement for how spread out your data is and is shown with a σ symbol
Null hypothesis – The idea that you are trying to prove wrong eg. That too much of your budget is going on coffee.
Alternative hypothesis – The idea that you are trying to prove right eg. The goverment is taking too much money from your budget.
http://www.null-hypothesis.co.uk/science//item/what_is_a_null_hypothesis a cool random website I stumbled on along the way