Course map
Planning and collecting data AQA Sections A and B · Edexcel Topic 1
- AQA A1, AQA A2, AQA A3, AQA SEC, Edexcel 1a.01, Edexcel 1a.02, Edexcel 1a.03
The statistical enquiry cycle and hypotheses
- Name the five stages of the enquiry cycle and what happens at each
- Write a hypothesis that data can test
- Plan around constraints such as time, cost, ethics and confidentiality
- AQA B1a, AQA B1b, AQA B1c, Edexcel 1b.01, Edexcel 1b.02, Edexcel 1b.03
Types of data and grouping
- Classify data as categorical, ordinal, discrete or continuous, qualitative or quantitative
- Weigh up grouping data into classes
- Name the explanatory and response variables
- AQA B2a, AQA B2b, AQA B2c, Edexcel 1b.04, Edexcel 1d.01, Edexcel 1d.02
Primary and secondary data, reliability and validity
- Compare primary and secondary data
- Choose a collection method: experiment, survey, observation, census or reference
- Tell reliability from validity
- AQA B3a, AQA B3b, AQA B3c, AQA B3d, AQA B3e, Edexcel 1c.01, Edexcel 1c.02, Edexcel 1c.03, Edexcel 1c.04, Edexcel 1c.05
Populations, sample frames and random samples
- Tell a population, a sample frame and a sample apart
- Take a simple random sample and a systematic sample
- Explain the bias risk in opportunity and judgement samples
- AQA B3d, AQA B3f, Edexcel 1c.03, Edexcel 1c.04, Edexcel 1c.06
Stratified and quota sampling
- Work out how many to take from each stratum
- Explain how quota sampling differs from a stratified random sample
- Choose a sampling method for a context and justify it
- AQA B2d, AQA B4, Edexcel 1d.03, Edexcel 1d.04
Questionnaires, interviews and bias
- Spot leading, ambiguous and overlapping questions and fix them
- Compare open and closed questions and interview methods
- Reduce bias from sensitive questions
- AQA B5a, AQA B5b, AQA B5c, Edexcel 1d.05, Edexcel 1d.06, Edexcel 1d.07
Cleaning data and controlling variables
- Find and deal with missing, mistyped and impossible values
- Use row and column totals to find a recording error
- Control extraneous variables, with control groups and matched pairs
Representing data AQA Section C · Edexcel Topic 2a
- AQA C1a, AQA E3d, Edexcel 2a.01
Tables, two-way tables and pictograms
- Complete a two-way table from given facts
- Read and draw pictograms with a key
- Read published tables and pick out what matters
- AQA C1a, AQA C2, Edexcel 2a.01, Edexcel 2a.03
Bar charts and pie charts
- Read dual, composite and percentage bar charts
- Work out pie chart angles and read frequencies from a pie chart
- Compare two pie charts of different totals
- AQA C1a, Edexcel 2a.01
Stem and leaf diagrams and Venn diagrams
- Draw and read ordered and back-to-back stem and leaf diagrams
- Find the median and range from a stem and leaf diagram
- Fill a Venn diagram from counts
- AQA C1b, Edexcel 2a.02
Population pyramids, choropleth maps and comparative diagrams
- Read population pyramids and compare two populations
- Read a choropleth map and its shading key
- Draw comparative pie charts with areas in proportion to totals (Higher)
- AQA C2, Edexcel 2a.03
Line graphs, time series and frequency polygons
- Read a time series graph and describe its trend
- Draw a frequency polygon at the class midpoints
- Compare two distributions with frequency polygons
- AQA C2, AQA D3a, Edexcel 2a.03, Edexcel 2c.01
Cumulative frequency
- Build a cumulative frequency table and plot at upper class boundaries
- Estimate the median, quartiles and percentiles from the graph
- Estimate how many values lie above or below a given value
- AQA C2, AQA C3b, Edexcel 2a.03, Edexcel 2a.04, Edexcel 2a.06 · Higher only
Histograms with unequal class widths
- Work out frequency density and draw a histogram
- Read frequencies from a histogram's areas
- Spot a histogram drawn with frequency instead of frequency density
- AQA C3a, AQA C3b, AQA C4a, AQA C4b, Edexcel 2a.05, Edexcel 2a.06, Edexcel 2a.07, Edexcel 2a.08
Choosing diagrams and spotting misleading ones
- Choose a diagram for the type of data and justify it
- Spot truncated axes, uneven scales and distorted sizes
- Move the same data between different diagrams
Averages and spread AQA Sections D and E · Edexcel Topics 2a to 2c
- AQA D1a, AQA D1b, AQA E3a, Edexcel 2b.01, Edexcel 2b.02, Edexcel 2b.03
Mode, median and mean
- Find the mode, median and mean of a list
- Choose the best average for a context and justify it
- Work out how adding or removing a value changes the mean
- AQA D1a, Edexcel 2b.01
Averages from frequency tables and grouped data
- Find the mean, median and mode from a frequency table
- Estimate the mean of grouped data from class midpoints
- Estimate the median of grouped data by interpolation
- AQA D1a, AQA D1b, Edexcel 2b.01, Edexcel 2b.02 · Higher only
Weighted mean and geometric mean
- Work out a weighted mean
- Work out a geometric mean and use it for growth rates
- Explain when the geometric mean beats the arithmetic mean
- AQA D3a, AQA E3b, Edexcel 2c.01, Edexcel 2c.04
Range, quartiles, interquartile range and percentiles
- Find the quartiles and interquartile range of a list
- Work out percentiles and the interdecile range
- Compare spread in context
- AQA C2, AQA D3b, AQA E5b, Edexcel 2a.03, Edexcel 2c.02, Edexcel 2c.03
Box plots and outliers
- Draw and read box plots, and compare two
- Test for outliers with 1.5 interquartile ranges (Higher)
- Decide whether an outlier is an error or a genuine value
- AQA D3a, AQA E3b, AQA E3c, AQA E11d, Edexcel 2c.01, Edexcel 2c.04, Edexcel 2c.05, Edexcel 2c.06 · Higher only
Standard deviation and standardised scores
- Work out the standard deviation of a list and a frequency table
- Compare data sets with mean and standard deviation
- Standardise scores to compare across two tests
- AQA D2, AQA E3c, AQA E5a, Edexcel 2a.09, Edexcel 2a.10, Edexcel 2c.05
Skewness and comparing distributions
- Spot positive and negative skew from a diagram or the averages
- Work out a skewness value from a given formula (Higher)
- Compare two distributions on average, spread and shape in context
Correlation, trends and index numbers AQA Sections D and E · Edexcel Topics 2d to 2f
- AQA E8a, AQA E8b, AQA E8c, Edexcel 2e.01, Edexcel 2e.02, Edexcel 2e.03
Scatter diagrams, correlation and causation
- Describe correlation as positive, negative or none, strong or weak
- Tell correlation from causation and spot a third variable
- Tell interpolation from extrapolation and judge each
- AQA D5, Edexcel 2e.04
Lines of best fit and regression lines
- Draw a line of best fit through the double mean point
- Read and use the regression line y = a + bx (Higher)
- Interpret the gradient and intercept in context
- AQA D6, AQA E9a, AQA E9b, AQA E9c, Edexcel 2e.05, Edexcel 2e.06, Edexcel 2e.07, Edexcel 2e.08 · Higher only
Spearman's rank and Pearson's correlation coefficients
- Rank two variables and work out Spearman's rank correlation coefficient
- Interpret a coefficient between -1 and 1 in context
- Explain when Spearman's and Pearson's differ
- AQA D4, AQA E6, AQA D1a, Edexcel 2f.01, Edexcel 2f.02
Moving averages and seasonal variation
- Work out 4-point moving averages and draw a trend line
- Work out the mean seasonal variation (Higher)
- Predict a future value from the trend and the seasonal variation
- AQA E7a, AQA E7b, AQA E7c, Edexcel 2d.01, Edexcel 2d.02
Index numbers and rates
- Work out and read simple and chain base index numbers
- Work out a weighted index number (Higher)
- Work out crude and standardised rates from a formula
Probability and distributions AQA Sections D and E · Edexcel Topics 2g and 3
- AQA D7, AQA E1a, AQA E1b, AQA E1c, AQA E2a, AQA E2b, Edexcel 3p.01, Edexcel 3p.02, Edexcel 3p.03, Edexcel 3p.04, Edexcel 3p.05, Edexcel 3p.06
Probability, expected frequency and risk
- Estimate probabilities from relative frequency
- Work out expected frequencies
- Work out and compare absolute and relative risk
- AQA E2c, Edexcel 3p.07
Sample spaces, two-way tables, Venn and tree diagrams
- List outcomes in a sample space diagram
- Find probabilities from two-way tables and Venn diagrams
- Use the addition rule for mutually exclusive and general events
- AQA E4a, AQA E4b, Edexcel 3p.08, Edexcel 3p.09
Independent events and conditional probability
- Use P(A and B) = P(A) × P(B) for independent events
- Work out conditional probabilities from tables and trees
- Test whether two events are independent
- AQA E10a, AQA E10b, Edexcel 3p.10, Edexcel 3p.11 · Higher only
The binomial distribution
- Check the conditions for a binomial model
- Work out binomial probabilities for small n
- Compare observed results with a binomial model to judge bias
- AQA E11a, AQA E11b, AQA E11c, Edexcel 3p.12, Edexcel 3p.13, Edexcel 2g.02 · Higher only
The Normal distribution and quality assurance
- Describe the shape of a Normal distribution
- Use the 68%, 95% and 3 standard deviation facts
- Set and read warning and action lines on a control chart
Estimation and sampling evidence AQA Section E · Edexcel Topics 2g and 2h
- AQA E12a, AQA E12b, AQA E12c, AQA E12d, Edexcel 2h.01, Edexcel 2h.02
Estimating population totals and capture-recapture
- Estimate a population mean or proportion from a sample
- Scale a sample result up to a population
- Use the Petersen capture-recapture formula and state its assumptions (Higher)
- AQA E13a, AQA E13b, Edexcel 2h.03, Edexcel 2g.01
Sample size, reliability and sample means
- Explain why larger samples give more reliable results
- Explain why sample means spread less than single values (Higher)
- Judge a conclusion by the sample it came from
