Hypothesis testing and report writing

Hypothesis testing is the discipline of deciding whether data support a claim or whether the result could be chance. The null hypothesis says 'no effect'; the test asks how surprising the data would be if the null were true. Worked example: if a coin comes up heads 8 times in 10 tosses, that looks suspicious — but under a fair coin, 8 or more heads in 10 tosses happens about 5.5% of the time, so at the usual 5% level it is just short of proof that the coin is biased.