Flashcards · 7357 · Topic 21

Use of data in statistics flashcards

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σ and s: Divisor n against divisor n − 1. Close for large n.
Missing and zero: A missing value is not a measurement of 0.
Error and outlier: An error is wrong and is corrected or removed; an outlier may be real.
Correlation and causation: Data from a survey can show association, not cause.
Summary and raw data: From n, Σx and Σx² you can find x̄ and σ, but not the median.
n = 10, Σx = 50 and Σx² = 290. Find the mean and standard deviation.: x̄ = 50/10 = 5. σ² = 290/10 − 5² = 29 − 25 = 4, so σ = 2.
The four requirements for using data in A-level statistics: Become familiar with one or more large data sets; use technology (spreadsheets or statistical software) to explore them; interpret real data in summary or graphical form; use data to investigate questions in real contexts.
What should you know about the AQA large data set?: Its contexts, its main features, and how technology helps to explore it. Exam questions may assume this familiarity.
Sample statistic vs population value: A sample statistic (such as x̄) estimates a population value (such as μ), and a different sample would usually give a different estimate.