Recall — GCSE Flashcards
📊 GCSE Statistics Flashcards
Data collection, averages, probability — 10 free revision cards. Study them below, or add the whole deck to Recall and let FSRS spaced repetition schedule your revision so it actually sticks.
Define mean, median, mode.
Mean: sum of values ÷ number of values.
Median: the middle value when ordered (average of two middle if even count).
Mode: the most frequent value (can be more than one or none).
Median: the middle value when ordered (average of two middle if even count).
Mode: the most frequent value (can be more than one or none).
What is the range and what is the interquartile range?
Range = max − min. Sensitive to outliers.
Interquartile range (IQR) = upper quartile (Q3) − lower quartile (Q1). The spread of the middle 50%. Resistant to outliers.
Interquartile range (IQR) = upper quartile (Q3) − lower quartile (Q1). The spread of the middle 50%. Resistant to outliers.
What is standard deviation?
A measure of spread around the mean.
$$\sigma = \sqrt{\dfrac{\sum(x - \bar{x})^2}{n}}$$
Low SD = data clustered near mean. High SD = spread out.
$$\sigma = \sqrt{\dfrac{\sum(x - \bar{x})^2}{n}}$$
Low SD = data clustered near mean. High SD = spread out.
What is the difference between discrete and continuous data?
Discrete: can only take specific values, usually integers (number of children, dice roll).
Continuous: can take any value in a range, measured not counted (height, time, temperature).
Continuous: can take any value in a range, measured not counted (height, time, temperature).
What is stratified sampling?
Divide the population into subgroups (strata) and sample from each in proportion to its size.
Example: If a school has 60% boys, 40% girls, a sample of 50 takes 30 boys and 20 girls. More representative than simple random sampling.
Example: If a school has 60% boys, 40% girls, a sample of 50 takes 30 boys and 20 girls. More representative than simple random sampling.
How do you calculate probability of independent events?
$$P(A \text{ and } B) = P(A) \times P(B)$$
Example: Rolling a 6 AND flipping heads:
$\dfrac{1}{6} \times \dfrac{1}{2} = \dfrac{1}{12}$
Example: Rolling a 6 AND flipping heads:
$\dfrac{1}{6} \times \dfrac{1}{2} = \dfrac{1}{12}$
What is conditional probability?
The probability of A given that B has already happened.
$$P(A | B) = \frac{P(A \text{ and } B)}{P(B)}$$
$$P(A | B) = \frac{P(A \text{ and } B)}{P(B)}$$
What is correlation? Distinguish from causation.
A statistical relationship between two variables. Measured by correlation coefficient (−1 to +1).
Correlation ≠ causation — two variables may move together due to a third factor (confounding variable) or coincidence.
Correlation ≠ causation — two variables may move together due to a third factor (confounding variable) or coincidence.
What is a histogram and how is it different from a bar chart?
A histogram displays continuous data in grouped intervals. Bars touch because data is continuous. Frequency density (not frequency) is plotted when intervals differ.
A bar chart shows discrete or categorical data — bars are separated.
A bar chart shows discrete or categorical data — bars are separated.
What is frequency density?
$$\text{Frequency density} = \frac{\text{frequency}}{\text{class width}}$$
Used in histograms when intervals have different widths, so that area = frequency.
Used in histograms when intervals have different widths, so that area = frequency.
These 10 cards are a free starter deck — a companion for memorising the core facts, not a complete course. In the Recall app you can also paste your own class notes and have AI build decks for the topics your exam board covers.