Question

In soccer, goals are often scored (and games decided) by penalty kicks. The website “538” reports that stalling by the goalkeeper’s team (“freezing” the kicker by taking the ball, refusing to line up, arguing with the referee, etc.) leads to a “statistically significant” decrease in the probability that the kicker will score a goal. Explain what they mean by the term, “statistically significant.”  

Answer 1

In soccer, goals are often scored (and games decided) by penalty kicks. The website “538” reports that stalling by the goalkeeper’s team (“freezing” the kicker by taking the ball, refusing to line up, arguing with the referee, etc.) leads to a “statistically significant” decrease in the probability that the kicker will score a goal. Explain what they mean by the term, “statistically significant.”  

Statistically significant means a possibility of an event occuring is not just by chance but due to some aforementioned reasons that is we reject the nullhypothesis. It is "statistically" because we conduct a hypothesis test where we make the decision of rejecting or retaining the null hypothesis (The event is happening due to a chance) with some probability of error (1% or 5% or 10%) attached to it.

Here, they say that low probability of scoring might be associated with delibrate goalkeeper's team's attempts. So we test this is claim where we say that

Null Hypothesis: The low probability of scoring is due to chance

lternative hypothesis: The low probability of scoring is associated with delibrate goalkeeper's team's attempts.

The result is statistically significant means we are rejecting the null hypothesis at some level of significance (probability of error) and concluding that the low probability of scoring is significantly associated with delibrate goalkeeper's team's attempts.