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Data Collection and SamplingEdexcel GCSE Maths: Flashcards

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What is the difference between a population and a sample?

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What is the difference between a population and a sample?
A population is the entire group being studied; a sample is a smaller group selected to represent it.
What is bias in sampling?
A systematic error caused by a sample that does not fairly represent the population.
Does a larger sample guarantee an unbiased result?
No — a large but unrepresentative sample can still be biased.
How do you calculate the angle for a category in a pie chart?
(frequency ÷ total frequency) × 360°.
45 out of 180 people chose 'blue'. What angle represents this on a pie chart?
(45 ÷ 180) × 360 = 90°.
What goes on the horizontal axis of a time series graph?
Time.
What is a 'trend' in a time series?
A general upward, downward, or repeating pattern shown by the data over time.
What does a stem-and-leaf diagram show that a frequency table might not?
Every original data value, while also showing the overall shape of the distribution.
What is a back-to-back stem-and-leaf diagram used for?
Comparing two data sets, displayed on either side of a shared stem.
What must always be included with a stem-and-leaf diagram?
A key explaining how to read the values (e.g. '3 | 4 means 34').
Which diagram suits categorical data best?
A bar chart, pie chart, or pictogram.
Which diagram suits continuous data collected over time?
A time series graph (or a histogram for continuous grouped data).