Does charting at home tell you a Korean title will travel?

Home run length against foreign reach

How a place is counted. One place is one title on one country’s weekly top 10. A title on the list for six weeks in Korea has six home places.

It is a slope, not a door. The median number of countries jumps from 1 to 19 between the middle two rows, which looks like a threshold — but the median only records where the middle title sits. The share reaching ten countries moves 11.4% → 25.5% → 56.5% → 63.2%. Nothing snaps; it leans.

The objection: is this just films against series?

Series stay on charts longer than films almost everywhere, so a band built on run length could simply be sorting formats. We split every band and left both columns in.

Both are true, and the format gap is the larger one. Inside every band, series reach ten countries more often than films — and in the 3–5 band the difference is 52.3% against 8%, wider than the whole home-chart effect. A film that ran six weeks at home still travels less often than a series that ran three. If you are reading one number, read the format first.

And the home chart is not a gate

29 titles reached twenty or more countries without ever appearing on Korea’s own top 10. They are not obscure abroad; they are absent at home.

Why we did not simply compare the two groups

560 of these titles charted in Korea and 355 did not. It is tempting to put those two groups side by side. We did not, and the reason matters: Titles that never charted in Korea are, by definition, titles we only know about because they charted somewhere else. Comparing the two groups directly would answer a question we have already decided.