Compare datasets
Pick up to four imported line-chart datasets and overlay their series on one graph. Use this when you want to see whether two or more published indicators move together, diverge, or change at different speeds over the same labels on the x-axis.
Chart
Series are aligned by matching x-axis labels; datasets with different time granularities (e.g. monthly vs yearly) won't line up perfectly.
How dataset comparison works
Search the catalog for datasets that have already been imported as line charts. Each slot is one dataset. After you choose a dataset, pick one numeric series from it — for example a single town, a national total, or another category the source table provides. The chart then requests aligned values from Data.ik.sg and draws them together. You can change a dataset, remove a slot, or add another until you reach the limit of four series. Nothing is submitted to a publisher; this is a local overlay of data already published on the site.
What you can compare
Typical uses include plotting HDB resale prices next to a consumer price index series, comparing COE premiums across vehicle categories, or lining up related labour and population indicators when those datasets exist in the catalog as line charts. Only datasets with a line-chart representation appear in search. Table-only, geospatial, and file-based datasets stay on their own pages because they do not share a simple numeric series that can be drawn on this graph.
Percent-change normalisation
Series often use different units and scales. A price in hundreds of thousands will dwarf an index that sits near 100. The normalise option rewrites every series so its first non-zero point equals 100, then plots later values as a percentage of that start. That makes the shape of change comparable even when the units are not. Turn it off when you need the original units on a shared axis.
Alignment and source limits
Series are aligned by matching x-axis labels, not by converting dates into a common calendar. A monthly label such as 2017-01 will not merge with a yearly label 2017, so mixed granularities can look staggered. Gaps in a source table appear as gaps in the line. Figures, column names, and licences remain those of the original publishers. Data.ik.sg is an independent catalog and does not replace the source documentation on each dataset page.