Regression and linear correlation
Scatter diagrams, Pearson and Spearman correlation, the regression line and worked IB exam questions for Applications and Interpretation SL.
When you know two pieces of data for each individual (hours of study and mark, temperature and electricity consumption), you want to know whether they are related and how strongly. You draw the scatter plot, measure the strength of the relationship with the correlation coefficient (Pearson's, or Spearman's when the relationship is not linear or the data are ordinal) and summarise it with the regression line, which lets you predict a value of one variable from the other. In the IB everything is obtained with the graphic display calculator; what is assessed is knowing what to ask it for, interpreting the result in context and judging whether the prediction is reliable.
Recommended order
Follow the sections in order: bivariate distributions, linear correlation, regression line and Spearman correlation. At the end you have the IB exam questions, grouped by type.
Descriptive statistics (topic 8).
Sections in this topic
Bivariate distributions and scatter diagram
Bivariate data: scatter diagrams, means, standard deviations, covariance and the mean point, using the GDC. IB Applications and Interpretation SL.
3 worked examples Section 2Linear correlation and Pearson's correlation coefficient
Linear correlation and Pearson's r: its sign and strength, computed with the GDC, and why correlation does not imply causation. IB Applications SL.
3 worked examples Section 3The regression line: fit, predictions and interpretation
Regression line of y on x with the GDC: predictions, interpolation versus extrapolation, and reliability. IB Applications and Interpretation SL.
3 worked examples Section 4Spearman's rank correlation coefficient
Calculating and interpreting Spearman's rank correlation: ranks, ties, the difference formula and Pearson comparison. IB Applications SL.
3 worked examples End of topicIB exam questions for topic 9
IB exam questions on regression: scatter diagrams, Pearson and Spearman correlation, regression lines and predictions, with step-by-step solutions.
45 exercises · 15 ★★★ levelStuck on this topic?
Tell us where you get lost and we will tell you how to tackle it. Álvaro replies on WhatsApp.
Message us on WhatsApp