Graphing and interpreting results

What type of graph should be used for continuous data?

Line graph.

What type of graph should be used for discrete or categorical data?

Bar chart.

What type of graph is used to show correlations between two variables?

Scatter graph.

What are the key features of a good graph?

• Title describing what is being measured.

• Labeled axes with units.

• Evenly spaced axes.

• Points plotted accurately.

• Line of best fit if appropriate.

What is a line of best fit?

A smooth line drawn through the center of the points to show the overall trend.

When should a line of best fit be straight vs curved

• Straight: Data shows a linear relationship.

• Curved: Data shows a non-linear relationship.

How do you describe trends in a graph?

State whether the dependent variable increases, decreases, stays constant, or shows a peak/plateau as the independent variable changes.

How do you spot anomalies?

Points that do not follow the overall pattern/trend.

How should anomalies be treated?

Identify them, suggest possible causes, and decide whether to exclude them from calculations.

How can rates be calculated from graphs?

Rate = change in quantity ÷ time (e.g., oxygen produced per minute).

What is interpolation?

Estimating a value within the range of recorded data.

What is extrapolation?

Estimating a value beyond the range of recorded data (less reliable).

How can gradients be used?

The gradient of a line shows the rate of change. Steeper gradient = faster rate.

Why is a line of best fit important for calculating rates?

It smooths out anomalies and gives a more accurate estimate of trends.

How can two datasets be compared effectively?

• Look at trends, peaks, and patterns.

• Compare gradients of lines for rates.

• Use percentages or ratios if scales are different.

What is the importance of scales on axes?

Choosing appropriate scales ensures data points are spread out and easy to interpret.