Choosing the Right Graph

Graphs are essential tools in science, particularly for HSC students. They allow us to understand complex relationships and trends, facilitating a better grasp of the underlying data. This article will introduce various types of graphs and discuss when to use each type, ensuring that you, as a HSC science student, can effectively communicate your findings and make informed decisions about data visualisation.

Line graphs

Line graphs are used to display continuous data over time, highlighting trends and patterns. They're particularly useful for showing how variables change over time, such as population growth, temperature fluctuations, or chemical reaction rates.

When to use: Use line graphs when you want to analyse trends or patterns over time, especially when time is a key variable.

Bar graphs

Bar graphs are used to display categorical data or to compare values across different categories. They use rectangular bars with lengths proportional to the values they represent. The bars can be arranged horizontally or vertically, depending on the data and the desired visual effect.

When to use: Use bar graphs when comparing data across categories or groups, such as different species, materials, or experimental conditions.


Histograms are similar to bar graphs but are used for continuous data instead of categorical data. They display the distribution of data by dividing the data into intervals (bins) and plotting the frequency of observations within each bin. Histograms can reveal the overall shape and distribution of the data, such as whether it is normally distributed or skewed.

When to use: Use histograms when you want to analyze the distribution of continuous data, particularly when looking for trends or patterns in the data.

Scatter plots

Scatter plots are used to display the relationship between two continuous variables. They consist of data points plotted on a Cartesian coordinate system, with each point representing the paired values of the two variables. Scatter plots can reveal trends, correlations, or clusters in the data, which can then be analysed using statistical methods.

When to use: Use scatter plots when you want to investigate the relationship between two continuous variables, such as the correlation between height and weight or the effect of temperature on reaction rates.