Does a higher price mean a bigger rise?
The height of a line is not a measure of its percentage growth.
The short answer
Price levels alone do not measure value, quality or future performance. Even in a simple educational comparison, the denominator determines the relative change. A shared price chart and an indexed chart each reveal something different.
A worked example
One illustrative price moves from £10 to £12. Another moves from £100 to £110. The second remains higher throughout and adds more pounds. The first increases by 20%, compared with 10% for the second.
Your turn
Use Compare Lab in Price mode, then switch to Indexed to 100. Explain why B is the higher line in one mode but A has the higher endpoint in the other.
What this does not tell you
An illustrative calculation does not explain causes or predict future results. Check the dates, units and missing observations before using the method elsewhere.
Related term
Absolute changeSources & review
Original Charts Haven example. All stated numbers are illustrative and allow you to repeat the calculation.
Next lesson: Compare the scales