I've always wondered what criteria is used when deciding which order the celebrities dance in.

This season Dani, Denise & Kimberley all danced first on three occasions each. Louis was never the first to dance.

However, Louis was the last to dance on four occasions, including the final, twice as many times as any of the others.

How much of an advantage do you gain by being the last to perform before the voting lines are opened?

Well, the criteria isn't clearly established, but on the bbc site it gives this general blurb:

Many factors are taken into consideration when the performance order is chosen. These include the tempo of each of the tracks, the dance styles, and the story-lines and props featured in each performance. The order is varied each week in order to keep some surprises for the viewers and to avoid predictability.

I think it helps to get good performance slots but it's an adjustive factor rather than a primary one. Jason and Russell last year had the last slot a few times, but neither of them won. Alex last year had pretty bad performance slots (she saw the second half of the show once, if that) but still got to the semi-finals. It's also worth bearing in mind the last performance is often one that follows a storyline or is impactual so is usually good in its own right. But the recency effect in general makes performing near the end a good thing, probably. By the final though I would think that effect is mostly lost.

Sometimes good/bad performance slots are contextual too, though. A meh routine may be meh in its own right but if it follows/precedes a very good dance or one that takes up peoples' attention (like the judges arguing in Louis's Waltz) it's likely to be forgotten.

I don't think it matters too much towards the end, but when there are a lot of couples left early dances can be forgotten.

I do think it should be divided fairly though, especially towards the end. Louis should have danced first at least once, and not been repeatedly near the end the past few weeks, and Denise should have had a later slot in one of the last few weeks.

Surely Louis dancing last each time last night could also have been viewed as a disadvantage for voting.
Some viewers may only decide to vote after watching a dance so that would indicate that the couples dancing earlier were left with more time to make that impression and gather votes?

I would guess Louis and Denise were put first and last due to the two Charlestons as if they both made it through they needed to have a dancer between them or we'd have 2 Charlestons in a row.

My feeling is that they tend to put wow dances last, the judges see all the training footage and the dress rehearsals so I reckon it's agreed which is the stand out wow dance and that goes last. Sometimes on the night that dance at the end doesn't go to plan, but I think in general it's expected to be a big crowd/judge pleaser!

Yep and in the same way they like to open the show with a superior and/or party dance to get the excitement going. If Louis was the party stopper (you know what I mean) of the series, Kimberley was definitely the party starter

Isn't there such a thing as a recency effect in which the last thing you see is what you remember most - especially if it was a good experience? Having said thatI don't think anything would have stopped Louis winning last night.

Not sure he would have won if he had fumbled over his routines, but as I said in another thread, Louis has been the most sure-footed, error-free constestant this series and quite possibly ever to be seen on Strictly.

I think that the last slot is reserved for the best dance and the first also for a good dance.

I think Louis went last or near the end a lot at the beginning to stop people turning over to X Factor, then he had his rough couple of weeks where he was in the middle.

The first dance is often very good and is used to measure all the other dances by and going last is definitely the pimp spot on Strictly. Louis went last, I think, because he had the showstopping salsa and showdance.

IIRC, Dani was the only one of the finalists who had never been on last (and I think she's almost always been in the first half of the show too).

Dani danced last in week 5.

Apparently the producers decide on the running order afterr watching the couples reherse on Friday ,as was the case at Wembley when quite late on Friday night Natalie got a text from the producers to say they were dancing last . Michael mentioned it on ITT