Interpreting Data

Understanding Scatter Graphs and Correlation

Familiarise yourself with scatter graphs which represent bivariate data (data with two variables).
The x-axis is used for the independent variable, and the y-axis is used for the dependent variable.
Observe the correlation, which might be positive (both variables increase), negative (as one variable increases, the other decreases), or there may be no correlation.
Correlation is not causation. Just because two variables correlate, doesn’t mean one causes the other.

Using Mean, Median and Mode

Understand the three measures of central tendency: mean, median and mode.
Use the mean when data is symmetrical and no outliers are present, as it takes into consideration all the values.
Use the median when the data is skewed or if there are outliers, as it represents the middle value when the data is sorted.
The mode is the value that appears most frequently, which can be useful for categorical data.
Remember each method can provide different insights, and often it is useful to compute all three.

Dealing with Outliers

Identify outliers, which are values significantly different from the others.
Understand that outliers can affect the mean but not the median or the mode.
Consider whether outliers should be included or excluded, based on the context of the data.

Understanding Range and Interquartile Range

The range is the difference between the lowest and highest values in the dataset. It gives a broad understanding of dispersion.
The interquartile range is the range of the middle 50% of the data. It helps to describe the spread of the data and is not affected by outliers.

Using Box Plots

Learn to construct and read box plots (also known as box and whisker plots).
Box plots provide a visual representation of the minimum, lower quartile, median, upper quartile, and maximum.
They are particularly useful for comparing distributions of datasets and identifying any potential outliers.

Frequency Tables and Histograms

Understand frequency tables; these give a clear tabulated summary of data.
Be able to read and interpret histograms, which display the information from a frequency table and help visualise the spread and skewness of data.

Probability and Relative Frequency

Understand that probability is a measure of how likely an event is to occur.
Learn how to calculate relative frequency, which is an estimate of probability based on collected data.

By mastering these skills, you will be able to interpret data effectively, an essential tool in countless fields, including statistics, finance, marketing, and beyond.