Margin of Error
The margin of error (ME) is the maximum expected difference between a sample statistic and the population parameter. For a sample mean, ME = z* × (σ/√n) or ME = t* × (s/√n). The confidence interval is then estimate ± ME.
Real World
YouGov polls ahead of UK general elections typically report a margin of error of ±3%, based on sample sizes of roughly 1,500 voters, directly shaping how news outlets headline the results.
Exam Focus
Show the margin of error calculation explicitly and state the confidence level before quoting the final interval.
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