When it aired on Saturday, ratings were in the 5% range; when it aired on Sunday, they were in the 7% range.
It is the same drama. The actors and script are unchanged, and only a day separates them.
This pattern did not deviate once across eight episodes.
3-line summary
1. Namkoong Min’s ‘Completion of Marriage’ had lower ratings every Saturday.
2. All four times, Sunday was higher by around 2%p.
3. Even the same drama can vary depending on its competition that day.
Is 7.2% high?
According to a MoneyToday report, Episode 10 of KBS 2TV’s weekend drama ‘Completion of Marriage’ recorded 7.2% nationwide when it aired on August 2, ranking No. 1 among the miniseries that aired that day.
But in the summer of the same year, SBS’s ‘Chief Kim’ reached 23% in its final episode. That was on July 25, one week earlier.
7.2% and 23%. They differ by a factor of three, yet both carry the label “No. 1.”
This article is about why numbers measured by the same standard can differ so widely.
Only the odd-numbered episodes are low
Placed side by side, the episode-by-episode figures compiled by Top Star News look like this. The drama airs on two consecutive days, Saturday and Sunday, so odd-numbered episodes air on Saturday and even-numbered episodes air on Sunday.
| Episode | Day | Rating |
|---|---|---|
| 1 | Sat | 4.4% |
| 2 | Sun | 6.4% |
| 3 | Sat | 5.3% |
| 4 | Sun | 7.2% |
| 5 | Sat | 5.0% |
| 6 | Sun | 6.4% |
| 7 | Sat | 4.8% |
| 8 | Sun | 7.3% |
Sunday won all four times. And by 1.5%p to 2.5%p each time—a gap too wide to call coincidence.
It is unlikely that the drama suddenly became more entertaining, then less entertaining again the following week, four times in a row. Therefore, the cause lies outside the drama.
What was on Saturday night?
The aforementioned ‘Chief Kim’ was an SBS Friday-Saturday drama. It was scheduled to air on Fridays and Saturdays.
It ended with its final episode at 23% on Saturday, July 25, and maintained No. 1 in miniseries ratings throughout its run.
Saturday-night viewers chose between the two dramas, while on Sunday night, that option was absent.
This is the part of the table I found most interesting. The difference between 4.8% and 7.3% is closer to a difference in how many places the remote control could go at that time than a difference in viewers’ assessment of the show.
Of course, broadcasters do not schedule programming without knowing this. Lower ratings on a day with strong competition are factored in, and they hold on with the expectation of recovering after that competitor ends.
These numbers are made by 4,300 households
Ratings are not figures produced by counting the entire population.
According to materials from the Korea Press Foundation, Nielsen Korea attaches measurement devices to TVs in about 4,300 households, while TNMS does so in about 3,200 households, automatically recording channels. This is the people-meter method used since 1990.
Two implications follow.
The sample is everything. 4,300 households stand in for 5,000만 people, with 만 denoting ten thousand. So there is not actually much significance in declaring victory or defeat over a 0.1%p difference. Sample surveys have margins of error.
Only people sitting in front of a TV are counted. Viewing on a smartphone, on the subway, or later through replay viewing is not included in these figures. The same materials identify this as a limitation.
In fact, as of August 4, ‘Completion of Marriage’ ranked No. 1 among Disney+ Korea series. Not a single one of those viewers is included in the 7.2%.
9.2% is a different figure
You may have seen “peak minute-by-minute rating” listed separately in articles. For Episode 8, it was 9.2%.
The people meter records viewership in one-minute intervals. That means the number varies from minute to minute within an episode, while the rating commonly cited is the average of those minutes.
7.3% is the average, while 9.2% is the highest-rated 1 minute of that episode. It is not measuring different data; it is slicing the same data differently.
The wider the gap between the two figures, the more viewers entered and left during that episode. When they are close together, it means viewers watched evenly from beginning to end.
That is why the final 5 minutes matter to a production team. If an episode ends by making viewers curious, the first minute of the next episode starts high. With consecutive Saturday-Sunday broadcasts, the gap is only 24 hours, making this a schedule that can recover viewers in just one day.
When looking at a single number, consider both the denominator and the competition. The denominator for 7.2% is 4,300 households, and the competition is other channels that night.
When you hear that a drama recorded a certain %, check the day of the week. If you also look at what aired alongside it that day, the number reads differently.
Episode-by-episode figures are freely available by date on the Nielsen Korea ratings page. Rather than showing only the figure for a single episode quoted in an article, it lets you see the entire week on one screen, making weekday differences for the same drama immediately visible.
Ratings are less a report card for a show than a record of that time on that night.
References
- MoneyToday ‘Completion of Marriage’ Namkoong Min becomes Kim Dae-myung’s murder target... ratings at 7.2% after a major-twist ending
- Top Star News ‘Completion of Marriage’ ranks high in TV drama buzz → ratings trend draws attention
- NewsPim Fantagio-produced ‘Chief Kim’ ranks No. 1 in 2026 miniseries ratings
- Wikitree Ratings surge past ‘7%’... Korean drama tops OTT rankings with just 2 episodes left before its finale
- Korea Press Foundation TV and Ratings Measurement
The ratings figures are Nielsen Korea’s nationwide figures and follow the reports cited above.