Movie rating.

Why movie rating goes down with a vote that goes up?
The movie UMA VIDA SUBLIME hat a movie rating of 6,2 with 99 votes. Then, someone vote 7, and the movie rating then down to 5.9. ??? How is it possible?

This conversation is no longer open for comments or replies and is no longer visible to community members.

Responses

Oldest First

Selected Oldest First

jeorj_euler

10.7K Messages

•

226.4K Points

7 years ago

Interesting.

0

Vincent_Fournols

2.4K Messages

•

81.2K Points

7 years ago

Hi Luis,

First, the overall rating is not the arithmetical mean of all registered rating. IMDb has a mysterious secret formulae that takes care of several factors, e.g. excluding rates from non registered voters. Some legit voters may also change there ratings (I can do it if my opinion on a movie has changed when watching it again). And maybe other reasons that IMDb would not disclose.

My belief is that there is a computation formulae, which is consistent for all entries.

9

luis_diogo_jn8z2dpcbt1q0

4 Messages

•

210 Points

Thanks. But in this case doesn't really makes sense because no ond changed vote. It was a vote of 7.
You just cannot have a formula where you go down after a vote that foes up. And the secret formula cannot be an excuse because the truth is thar now I don't know if they make it on purpose. Is imdb credible os are they controled by other values. They put Uma Vida Sublime down 4 days before it opens in cinema. Just a coincidence?
Someone should investigate this.

7 years ago

Vincent_Fournols

2.4K Messages

•

81.2K Points

Not necessarily: you show us two snapshots, one with 99 votes, one with 100, with almost exactly the same breakdown. But actually you may have had -4+5 and these 9 gap votes may impact the overall rating differently.
I do not say that this is what happened, but mathematically speaking, it could happen.

In any case, I do not think IMDb will share any investigation, if any: absolutely all requests regarding the change of ratings and overall computation have always been ignored...

7 years ago

ACT_1

8.9K Messages

•

180.4K Points

Reply to Vincent Fournols
IMDb has a mysterious secret formulae

- - -

I do not understand any of this - You want to play with the Numbers ? ?

https://en.wikipedia.org/wiki/IMDb
https://en.wikipedia.org/wiki/IMDb#User_ratings_of_films

W = R.v+C.m
        -----------
          v+m
where:
W       = weighted rating
R       = average for the movie as a number from 1 to 10 (mean) = (Rating)
v       = number of votes for the movie = (votes)
m       = minimum votes required to be listed in the Top 250 (currently 25,000)
C       = the mean vote across the whole report (currently 7.0)
The W   in this formula is equivalent to a Bayesian posterior mean (see Bayesian statistics).
.

= = =

BonaFideBOSS : Poll Tracking, Statistics

Jessica : Poll Board Suggestions

IMDb Picks

IMDb Events

IMDb Best Of 2024

IMDb Editors's Lists 3300+

IMDb Statistics Total Data Items, Titles, Names...

IMDb Top Data Contributors for January 2025

IMDb Contribution

IMDb Data Processing Times

IMDb Leadership Change Jan 21 2025

Your Contribution History | Update History

7 years ago

Vincent_Fournols

2.4K Messages

•

81.2K Points

I fully trust you, ACT! :D

7 years ago

ACT_1

8.9K Messages

•

180.4K Points

If I said I was a liar - would I be telling you the truth ? ?
.

= = =

BonaFideBOSS : Poll Tracking, Statistics

Jessica : Poll Board Suggestions

IMDb Picks

IMDb Events

IMDb Best Of 2024

IMDb Editors's Lists 3300+

IMDb Statistics Total Data Items, Titles, Names...

IMDb Top Data Contributors for January 2025

IMDb Contribution

IMDb Data Processing Times

IMDb Leadership Change Jan 21 2025

Your Contribution History | Update History

7 years ago

Vincent_Fournols

2.4K Messages

•

81.2K Points

It depends on the stakes... ;)

7 years ago

luis_diogo_jn8z2dpcbt1q0

4 Messages

•

210 Points

9 gap votes??? There is just one vote more . What's the doubt about this? Just one more person voted 7. Is pure math: you cannot have your average down with a new higher vote.

7 years ago

Vincent_Fournols

2.4K Messages

•

81.2K Points

No, it is one more aggregated votes, but you do not know how many could have been removed (for whatever IMDb reason) when the same number plus one being added. And maybe among these latter ones, some do not qualify to be computed into the overall rating. So the breakdown by votes, and any change between two snapshots can hardly give any clue on the way the overall rating will change.

7 years ago

jeorj_euler

10.7K Messages

•

226.4K Points

As Vincent Fournols suggested, it is possible that a VIP swapped votes with a non-VIP, so to speak. Am I making sense? And as ACT_1 suggested, it is not the formula that is proprietary but the the identities of voters along with whether or not their votes are weighted, how much and how the weight assignment to the voter was determined.

— Jeorj Euler, an IMDb regular registrant

7 years ago

Col_Needham

Employee

•

8.5K Messages

•

194.4K Points

7 years ago

Thank you for sharing your concern, generally all we can say about voting is covered in the FAQ at https://help.imdb.com/article/imdb/track-movies-tv/faq-for-imdb-ratings/G67Y87TFYYP6TWAV

However, we can add one more piece of detail for this case since the answer is right in front of everyone's eyes. For titles < 100 votes, the weighted average is the arithmetic mean; once a title hits 100 valid votes (or more) the IMDb weighted average formula kicks in.

5

Vincent_Fournols

2.4K Messages

•

81.2K Points

Thanks Col, this is interesting to know.

7 years ago

jeorj_euler

10.7K Messages

•

226.4K Points

O, yeah...

— Jeorj Euler, an IMDb regular registrant

7 years ago

luis_diogo_jn8z2dpcbt1q0

4 Messages

•

210 Points

Thanks. That is a explanation I can accept. But of course could not be the formula.
Next time with 99 votes i will ask people not to vote more. Eh, eh. Or if i ask someone to delete his vote the average will go up? Strange

7 years ago

belinda_bennett_4nmkff0lnrcbe

18 Messages

•

448 Points

It’s generated as a median of the whole votes, so if you had 10 people vote 5/10, the median would be 5. If 6 of them voted 4/10, the rest voted 6/10, the median would be 4.

7 years ago

belinda_bennett_4nmkff0lnrcbe

18 Messages

•

448 Points

Why are commas used instead of full stops when showing fractions? I. E. 6,2 rather than 6.2

7 years ago

luis_diogo_jn8z2dpcbt1q0

Movie rating.

jeorj_euler

Vincent_Fournols

luis_diogo_jn8z2dpcbt1q0

Vincent_Fournols

ACT_1

Vincent_Fournols

ACT_1

Vincent_Fournols

luis_diogo_jn8z2dpcbt1q0

Vincent_Fournols

jeorj_euler

Col_Needham

Vincent_Fournols

jeorj_euler

luis_diogo_jn8z2dpcbt1q0

belinda_bennett_4nmkff0lnrcbe

belinda_bennett_4nmkff0lnrcbe

Related Conversations

Helpful Widget