As Flyman is off on his little hollibob soon, he has kindly asked me to set up the new CTC thread for this season, for discussion of price changes and the predictions thereof. So with kickoff in sight, here it is.

For now the opening posts are largely copied from Flyman's work from last season, but I will regularly update any changes to key info regarding the CTC site and/or calculation methods throughout the season.


THE FISO GUIDE TO FPL PLAYER PRICE CHANGES

This season's Price Change Site, aka "CrackTheCode", can be found HERE.

*Update 19 Aug: CTC is now live! We are indebted to forum member diamondplus for his creation of this site, to enable us to use this information.


The mechanics / formulae behind the price changes are described in the next post, as accurately as we currently know them.



PLEASE NOTE:
! The CTC site is (currently) updated every day at 09:00, 13:00, 16:00, 18:00, 19:00, 20:00, 22:00.

! FPL.com price changes occur between 00:30 and 03:30 each day.

!Note! Price drops for players with less than 1% ownership (see FPL site) can not be deduced and are not included.

! The rise and the fall thresholds will vary over the season. Any changes to this algorithm will be reflected on diamondplus's site at his earliest opportunity. For this reason users must accept the possibility of inaccuracies on the site.

! There is a margin of error of 1% implicit in all 'Price Drops: Selected By' statistics due to the limited details FPL.com give managers. This small margin of error can sometimes result in prices not falling when predicted by the site.



IMPORTANT!
1) FPL.com's algorithms are secret and may take some time to determine. Please bear with the FISO Boffins during the refining process.
2) This information is used at your own risk.
diamondplus maintains this website in his spare time and for no financial reward. While he will endeavour to keep it up to date this is not always immediately possible and he is under no obligation to do so at all. Users must take responsibility for their own actions. FISO and diamondplus accept no responsibility for errors on the site, nor for the actions of those using the site as a guide to price changes.

IMPORTANT NOTES

Price rises and falls occur due to transfer activity among FPL managers.

Price changes depend on Net Transfers In (NTI) = transfers in - transfers out.

Counting a player's NTI:
A player's NTI is clocked up continuously from day 1 of the season and is reset only in the following cases:

(1) When the player rises or falls in price
(2) After a player's red (i) status is removed following an injury/suspension (after the 10 day protection period)
(3) After a player transfers to a PL club from outside the Premier League

(NOTE: they are NOT reset at gameweek deadlines)

The only thing to be reset at a gameweek deadline is a player's rise/drop target (if it had been doubled in the previous gameweek following a rise).


Price Rises:
Player price rises occur when a set number of Net Transfers In (NTI) have occurred.

The NTI at which a player's price is increased by 0.1m is known here as 'the NTI Threshold' or 'rise target'.
The NTI Threshold is decided by FPL themselves. The NTI Threshold at the start of this season was approximately 27,000, but will vary over the course of the season. (And see notes 3-5 below, for special rules for players rising more than once in a single gameweek)

Price Falls:
Price falls of 0.1m occur when a player's NTO (NTO = Transfers Out - Transfers In) reaches a particular number. We call this number the 'Fall Threshold'. A player's Fall Threshold is determined by a fall of X% of a player's ownership in the transfer market, where 'X' is a number decided upon by FPL.com.
That number is currently circa 10%.
(And see notes 3-5 below, for special rules for players dropping more than once in a single gameweek)

A player's Fall Threshold is determined by FPL as follows:
If 10% of managers owning a player sell him his price falls by 0.1m.
(Solely for the purposes of this explanation I shall assume the FPL's chosen % is 10%, as the true figure is both variable, and not exactly known.)

But how many is 10% of his total managers?
To establish this figure, first find the '% of Managers Owned By' stat from that player's (i) profile.
Then find the 'Total Players' stat (on My Team page and others).
Divide that by 100, then multiply the result by the % he is owned by.
This gives the total number of managers who own him at the moment.
Next, divide that figure by 10 to establish what '10% of Managers who own him' is.
This figure is his NTO Fall Threshold. When this number of net transfers out occurs his price will fall by 0.1m.




* Price drops for players whose price is above their initial value

A player whose price is above their initial value may still follow the rules above when it comes to dropping if his ownership is low enough. However players where the absolute value of the 10% threshold will be greater than the NTI threshold will fall at the negative NTI threshold.


Note:
1) Players' prices will only rise or fall by a maximum of 0.1m per day.

2) NTIs and NTOs in excess of any threshold are not carried over towards the next price change when that threshold is passed, but are 'lost to the economy'. After any price change the counter is reset to zero and a new count commences.

3) Any second rise or fall that gameweek will require two times the original number of NTIs or NTOs, respectively.

4) Any third rise or fall that gameweek will require three times the original number of NTIs or NTOs, respectively.

5) At the end of any given gameweek the thresholds return to their basic level.

Consequently, any player who has risen in price once that week (getting circa 27K NTI) and finds himself somewhere between the First Rise Threshold and the Second (getting yet another (circa) 27K - 54K NTI) on Friday (or the last day of that gameweek) is guaranteed to rise on the first update of the new gameweek when the NTI Threshold returns to 27K.


Flagged Players:

1. Injured, doubtful, ineligible and suspended players will continue to rise or fall. The rise threshold remains as normal, but the fall threshold is increased to around 22.5%. Players with a prior price increase will fall at the 22.5% threshold OR 2.5 x negative rise threshold, whichever is lower (see note * above).

2. When a player returns to fitness/eligibility (grey "i") the following conditions apply:

Only having been red flagged for one day, or yellow flagged: Reset to 0 and count begins immediately

Red flagged for more than one day: Transfers will not count for ten days, the price will not change during this limbo period. After 10 days the count is reset to 0 and transfers have their normal effect.



Transferred Players:

Players transferred into the Premier League in real life will be exempt from price changes for ten days from being added to the player list. Their price will not change during this limbo period. After 10 days transfers have their normal effect with the count starting at 0.

Thread History

The original 'Code Thread' can be found here: Cracking the Code - A FISO Guide to Determining Price Change'.
'Page 1, Post 1' contains a summary of how the FPL.com price fluctuations were determined in the 2006/07 season.

The 'Roll of Honour', acknowledging the contributions of those members involved in this endeavour, can be found here.

At the start of the 06/07 season members of FISO set out to determine how player price changes were decided in the FPL.com game.

Despite the limitations of the information available to us we succeeded - near as dammit, anyway!

What started as a manual effort was, throughout the season, refined by the membership. Our IT experts were eventually able to provide all the information we require, available at the click of a button!

The pinnacle of this group achievement came when diamondplus automated the stats-gathering process and provided a webspace available to us all!

The 2007/2008 Price Change Thread built on the previous season's successes and can be found here.

And last season's thread: 2008/09 CTC thread

I thought Jimmy Riddle was the "holibob" guy

Be interested to know how D+ got on over the summer with his proposed re-writes?

Will prices immediately start changing based on popularity of initial teams against the preset prices?

No. At the first deadline, all players will be considered to have zero net transfers against their name, i.e. pre-season buying and selling makes no difference.

Just curious, but going on the average time taken in previous seasons, how long does it normally take to figure out the NTI threshold?

Well we first have to wait until some players change in value. Then we make a wild stab in the dark as to what the thresholds are. Then as further players change in value, the thresholds can be refined. You could review the thread from last season (linked in the 3rd post of this thread) to see the process in action!

I knocked something up but a) it was never finished and b) I'm running out of time.

On the plus side I've now aqcuired a new faster PC so, for now, I'll stick with the existing rusty-but-trusty method.

Hardware > Software

Heres to another year of checking the CTC website thrice a day to see whether bandwagon A or bandwagon B seem to be generating more steam... cheers

So hows this CTC work then and what are u looking for?

Oh my God, will it be working today?

It cannot possibly start working until at least one player has risen and one player has fallen. Even then, we'd be making wild guesses until we have several risers and fallers. In the meantime, use the info on the FPL site to track GW transfers in and out totals. If you have Razza's script (see sticky in this forum) it will calculate the net gain/loss for you. This will at least allow you to see who the masses are transferring in and out.

As an indicator, the rise threshold started last season somewhere around 20k, and I think the season before it was about 15k (I suspect it was higher last year due to increase in total number of teams in the game, so I expect another higher starting threshold this year, maybe in the region of 25k)

And in anticipation of people worrying about the following two players: Gerrard and Arshavin are both owned by plenty of teams (33% and 21% respectively), so their drop thresholds will not be lower than the rise threshold.

i dont understand about the price fall.. and i already read about "how many is 10% of his total manager?". but h0w do we suppose to know about the total manager if the total player is unconsistent? should i take the total player at exact time or at the begining of the season?

Beginning of the season or the last price change I think.

When do the first price changes occur?

I would find last years thread and read it

Fabregas up almost 10k already

Looks llike my wildcard team is not going to be possible any more... too many have scored well and looking more likely to rise.

The train may slow a little on Mon/Tue when the hoi paloi look to see who his opponents are in GW2.

I can't see it.

When do the first price changes take effect?

Thanks.

As soon as enough transfers have been made to merit a price change.

No one knows how many transfers are required yet (assume it's around 20k though), but as soon as the first price rise happens we'll have an idea.

Last years thread can be found here:

the-fiso-guide-to-fpl-price-changes-the-code-thread-08-09-t53458-70.html

When they do,the CtC thread will be kick started,but presumably you will already know from having read the explanatory notes,that the changes only take place once,at night, usually between midnight and 2 a.m - the time varies,but averages about 1 a.m. The Ctc thread is updated several times each day,with the latest indications.

Sorry for not including the link, but it is at the top of the thread.

The bottom line is that once a pattern for price changes emerge, someone writes a program, which (relatively successfully) predicts future changes. Please note that this is not as simple as it seems.

So until there is a pattern, there is a lot of guesswork, and this thread is where people suggest patterns/trends from which the algorithm can be deduced.

Estimating at a 25,000 rise threshold here's the top 18 players at the mo, I know it can be got from the site but thought it may tide people over till CTC is up and running.

thanks very much fellas.

looks great.
I didn't play FPL last year; how much of a difference did the value changes make over the season? How much would a good squad value have been by the end of the season?