Your Verdict on The Zygon Invasion & Episode Ranking

Joshua Yetman reveals DWTV’s community episode score and ranking for the 7th episode of Series 9.

Nearly five-and-a-half thousand in Doctor Who TV’s polls last week for The Zygon Invasion, the seventh episode of Series 9, written by Peter Harness. Now it’s time to reveal the results. As usual we asked you to give the episode a score out of 10, and the pleasantly smoother score distribution of this particular episode (at least compared to the previous episode) is presented below:

For an episode that seemed to be so polarising on initial reception, the results are remarkably positive and – as we’ll see later – relatively congenial amongst the DWTV community.

Anyway, I’m sure you know the drill by now; each week we’ll be taking these votes and working out the average score. We will then use these averages to rank the episodes and get a rough idea of its placing in the series.

Here, the average score for The Zygon Invasion stands at an exceptionally impressive 8.325, and it’s a score that I can only shower in unadulterated praise as we shall see in section 1. This score puts The Zygon Invasion as the fourth best episode this year:

So, entering the second half of Series 9, the official rankings attained so far – and the corresponding (and rather impressive) ratings associated with each one – look like this:

• 1. The Witch’s Familiar – 8.603
• 2. The Magician’s Apprentice – 8.479
• 3. Under the Lake – 8.434
• 4. The Zygon Invasion – 8.325
• 5. Before the Flood – 8.181
• 6. The Woman Who Lived – 7.715
• 7. The Girl Who Died – 7.461
• The Zygon Inversion – TBC
• Sleep No More – TBC
• Face the Raven – TBC
• Heaven Sent – TBC
• Hell Bent – TBC

The Series 9 average has risen– for the first time in five weeks – from 8.146/10 to 8.171/10.

(1) Interpreting the score

Well, to address the elephant in the room, I think we can now firmly conclude that Series 9 isn’t progressively declining as the weeks advance, a mild concern I had a few weeks ago when I noted the waning nature of the scores. Indeed, Series 9 is now firmly back into 8+ territory for the first time since Before the Flood, and it’s not just on the cusp of this hallowed and well-respected region, but comfortably implanted in it as well.

8.325 is an excellent score in the grand scheme of things, as our trusted box and whiskers diagram below shows:

To clarify for any newcomers, this diagram represents the spread of episode quality in the revival. The box in the middle represents the middle 50% of all the 117 episodes between Rose and Last Christmas in terms of quality, distinguished into an upper quartile (the yellow section) and a lower quartile (the grey section), with the line between them being the median (i.e. the episode right in the middle of the rankings, which happens to be Time Heist). The ‘whiskers’ represent the absolute extremes of the revival, from The Day of the Doctor at the far right, to Fear Her at the far left. All the sample data for this diagram comes from the Rank The Revival census carried out earlier this year.

The position of The Zygon Invasion is demarcated by the black cross. Evidently, then, this episode is sitting comfortably on the upper whisker of the revival, i.e. putting it in the top 25% of episodes since 2005. In fact, to be more precise, it is in the top 23%.

Up there in the topmost class of episodic splendour, The Zygon Invasion is surrounded by acclaimed episodes such as Turn Left (marginally higher at 8.344), The Satan Pit (slightly lower at 8.258), and The Stolen Earth (marginally higher at 8.363) and, from the Matt Smith era, it even managed to trump the mid-series masterpiece that was A Good Man Goes to War (which attained a score of 8.251).

Overall, it would rank as the 33^rd highest rated episode in the revived series, at least using the current scores. And that’s brilliant.

Now, for our usual round of flash facts:

• Out of the 20 (yes 20 – doesn’t time fly!) rated episodes in Peter Capaldi’s era to date, The Zygon Invasion would proudly stand in 8^th place, between Under the Lake (8.434) in 7^th and Deep Breath (8.238) in 9^th.
• So how does the episode fare amongst other Episode 7’s? Well, a bit of context first. After Under the Lake pulled the Episode 3 slot out of bottom place, the Episode 7 slot took its place. Since then, the Episode 7 slot has been biding its time, hoping for long-awaited revenge, and The Zygon Invasion is just the kind of episode it was hoping for. Officially, The Zygon Invasion has become the highest rated Episode 7 of the revival (which isn’t saying much as Episode 7’s are usually poorly received) thus making the Episode 2, 3 and 7 slots currently dominated by Series 9 episodes. The closest Episode 7 competitor to The Zygon Invasion is the aforementioned A Good Man Goes to War, at 8.251. As a result of this, the Episode 7 slot average has jumped to 7.109…which is higher than the Episode 3 slot average of 7.045! Revenge is sweet!
• The modal (i.e. most common) score for The Zygon Invasion was 10, the first episode since The Witch’s Familiar to attain this. Furthermore, 93.49% of you have The Zygon Invasion half-marks (5/10) or more, the fifth highest of the series to date and the 61^st highest case of this in the revival.
• Also, the percentage of 10/10 votes for this episode – 33.65% – is the third highest this series (only being beaten by both halves of the opening story), and is the 27^th highest 10/10 proportion in the history of the revived series.
• The Zygon Invasion is the 11^th highest rated first part to a double-parter.
• It’s safe to say that Peter Harness has considerably outdone his first episode (Kill The Moon). In fact, he’s completely trounced his incredibly divisive initial effort, which scored a relatively lacklustre 6.809. However, this does make him the third least consistent writer in revived-Doctor Who history, only behind Neil Gaiman and Matthew Graham. Hopefully The Zygon Inversion can even this out a bit.

(2) The divisiveness of the story

Upon initial broadcast, I received the impression that this episode was distinctly polarising fans into ‘loved it’ and ‘hated it’ camps, with very little middle ground. This was very reminiscent of Harness’ first effort, Kill The Moon, but, whilst that episode went on to attain a very high standard deviation in the end, The Zygon Invasion, as it turns out, has defied my first impression completely. Well not completely, but certainly noticeably.

To reiterate, the divisiveness of an episode can be measured using standard deviation, a very handy statistic which measures how spread out votes are from the average. The higher the standard deviation, the more divisive the episode.

As it turns out, the standard deviation of The Zygon Invasion was 1.984. It’s higher than a lot of the episodes this series, but it’s a far cry from the 2.235 achieved by Kill The Moon. Plus, I can’t stress how nice it is to have a standard deviation below 2 again (we haven’t had such an episode since Before the Flood). Hopefully it will stay like this for some time, but, with historically divisive Mark Gatiss’ latest episode Sleep No More on the horizon, I wouldn’t bet money on it.

To make additional sense of what this number means, I have generated the following rough scaling system for interpreting standard deviation in the context of Doctor Who episodes:

• Less than 1.5 – very high agreement amongst the fanbase; whatever the overall opinion is of this episode, positive or negative, the vast majority of people conform to it.
• Between 1.5 and 1.75 – not particularly divisive.
• Between 1.75 and 2 –fairly divisive
• Above 2 – considerably divisive; opinions vary far and wide for such an episode.

So The Zygon Invasion sits high in the ‘fairly divisive’ bracket as far as this scaling system goes, but it’s still much less than I anticipated, and I can’t say I’m not relieved. For additional information, The Zygon Invasion is the 39^th most divisive episode of the revival, being slightly more divisive than 2012’s Dinosaurs on a Spaceship (which had a standard deviation of 1.977), but not as divisive as 2011’s The Girl Who Waited (which had a standard deviation of 1.991). It is the third most divisive episode this year.

Thus, the divisiveness rankings of Series 9 currently stand as such:

• 1. The Girl Who Died – 2.235 (most divisive)
• 2. The Woman Who Lived – 2.178
• 3. The Zygon Invasion – 1.984
• 4. The Magician’s Apprentice – 1.815
• 5. The Witch’s Familiar – 1.758
• 6. Before the Flood – 1.723
• 7. Under the Lake – 1.548 (least divisive)
• The Zygon Invasion – TBC
• The Zygon Inversion – TBC
• Sleep No More – TBC
• Face the Raven – TBC
• Heaven Sent – TBC
• Hell Bent – TBC

(3) Series 9 to date

Ah, Series 9. I just love how amazing you are performing! Seriously, on average 28.54% of the votes have been for the 10/10 score option, and a further 22.50% for the 9/10 score option. That is higher than any series to date. The initial Series 9 average (to date) of 8.171 dwarfs that of the initial Series 8 average (8.027) and Series 7 average (7.876, ignoring The Snowmen) by this stage in the series.

Speaking of the current Series 9 average of 8.171, it’s the first time in five weeks that it’s actually increased, a trend that will hopefully continue with a string of promising stories ahead of us. Consequently, the Qualityometer, our informal measure of how much better Series 9 is doing compared to the pre-Series 9 revival average, has also risen for the first time in five weeks, from 8.54% better than the pre-Series 9 average to just 8.88% better, as shown below:

Astute readers may notice that the Qualityometer has been recalibrated since last week, with the scale being reduced from -25% to 25%, to -15% to 15%. This is because we have arrived at the point in the series where the overall Series 9 average becomes less and less affected by newcoming episodes, meaning that – if we stick with the old scale – differences in the Qualityometer week-on-week would become very hard to see in the diagram. Reducing the scale is also more appropriate as it’d be nothing short of a miracle for any series to achieve more than 15% than the pre-Series 9 revival average; that’d mean averaging 8.631 – not even the highest rated episode so far this series achieved that. So this scale is more sensible anyway.

In any event, it’s great to see the Qualityometer rising, and may it keep rising for as long as possible.

(4) Evaluating the projections

A few months ago, I produced a set of statistical projections for the initial community averages of each upcoming episode in Series 9. The purpose of this was to compare them to the actual results as they became available, in order to gauge how sensible it is to use statistical models to forecast such potentially unpredictable variables. For the last two weeks, the projections were horribly wrong. This week, however, it was much closer to the mark. Sort of.

The estimate using my Oswald Model was 8.10, which represents an acceptable error of 2.76% now that we know the actual figure of 8.325. It could have been worse, I guess.

(5) Conclusion

In this and following edition of the “Your Verdict On…” series, I will incorporate a conclusion to summarise all the key statistics of the episode in hand.

So, for the inaugural conclusion, what else can I say about The Zygon Invasion other than the fact it came with many pleasant statistical surprises! I didn’t anticipate it to be so strongly rated, nor as congenial as it actually was. I suppose that’s a testament to how comment sections are not a good indicator of the ultimate results, which makes sense. Naturally, people in the ‘loved it’ and ‘hated it’ camps would flock to comment sections to declare their opinions, conveyed by the emotion underlying their attitude, wrongly giving the impression that the whole fanbase must be split into ‘loved it’ and ‘hated it’ camps as a result. As it turns out, there was much more middle ground than I foresaw. And a hell of a lot more ‘upper’ ground.

So join us next week when we get to grips with the statistics of the concluding half to this story, The Zygon Inversion, which will be a very interesting one indeed. This is because, as we now know, it carries an extremely powerful and rather iconic secret weapon that may – just may – give even The Witch’s Familiar, sitting at the top of the rankings, a run for its money. I can’t possibly call it at this stage, but I am very excited to see how well it will perform in the end.

Until then, keep voting!