Statistic
A statistic is a numerical property of a sample, calculated from the observed data. Common statistics include x̄ (sample mean), s² (sample variance), p̂ (sample proportion), and r (sample correlation coefficient). A statistic is a random variable because its value varies from sample to sample.
Real World
When Ipsos polls 1,000 UK voters before a general election, the percentage backing each party is a statistic — it changes with every fresh sample of voters they survey.
Exam Focus
State clearly that a statistic is a random variable because its value changes from sample to sample.
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