Diskussion:Monty Hall-problemet

message: Så er der igen tilføjet en simulering af problemet, og det bringer antallet af eksterne henvisninger op på 15, hvoraf omkring halvdelen består af eller indbefatter simuleringsprogrammmer. Det er efter min mening ganske enkelt for meget! Artiklen er i forvejen forsynet med rigtig mange fodnoter og (skriftlige) kilder, så derfor må man kunne skære ned i link-antallet uden at svække artiklens troværdighed og/eller dens informationsværdi. En til to simulatorer burde være tilstrækkeligt. --Arne (Amjaabc) 25. jan 2008, 16:14 (CET)
thread_title:  For mange eksterne henvisninger 

message: I'm sorry I cannot write in your language, but I do enough understand it as to comprehend the article. As in most other languages the given explanation is not correct. It gives the solution to a slightly, but essential other problem. The real problem as stated has the condition that the door that is chosen and the door that is opened and revealing a goat are both known to the player. This excludes possibilities in which the other door is opened. Many people does not see the difference with the problem, in which the chosen door is known, but the presentator explains his plans to the player, and before opening one of the othere doors, asks the player what he intends to do if a door is opened. The presented solution is the right one for the last case, but not for the real problem.
In more formal mathematics: Let X be the door behind which the car is, Y the door chosen by the player and M the door opened by the presentator, then when Y=1 (conditional that door 1 is initially chosen): 
replies: text: P(X=2|M=3,X\ne 3)=\frac{P(M=3|X=2)P(X=2)}{P(M=3,X\ne 3)}=
replies: text: :\frac{P(M=3|X=2)P(X=2)}{P(M=3,X=1 \cup M=3,X=2)} = \frac{\frac 13}{\frac 12 \times \frac 13 + 1\times \frac 13}=\frac 23
Nijdam 7. feb 2009, 23:14 (CET)

text: : As far as I can see the difference between the problem as it is stated here in Danish and your formulation is that the contestant makes his decision whether or not to change doors after the presenter has opened a door behind which a goat is found. How does this change the probability of the choice when the contestant always knows that the door opened by the presenter is a goat-door? --NiceGuy152 15. aug 2009, 12:30 (CEST)
replies: text: ::Well, probabilities don't change. If an event has occurred, the probabilities of interest are the conditional ones given the occurred event. Nijdam 8. dec 2009, 22:16 (CET)
replies: text: :::I'm unsure as to what needs to be corrected then. Should the problem be formulated such that the player knows both his chosen door and which door the host reveals to contain a goat, before making the choice as to which door he finally wants.--NiceGuy152 11. dec 2009, 15:19 (CET)
thread_title: Explanation

message: I artiklen argumenteres der for at det er en lovende strategi at ændre sit valg.
Der bliver forelagt en YDERST grundig argumentation.
Der bliver lavet figurer.
Der bliver konstrueret formler, som ser yderst matematisk-logiske ud.
Argumentationen er muligvis konsistent. Den er vistnok også forkert.
"Monty-Hall-problemet" er nemlig et spil, hvor reglerne ændrer sig undervejs - man må se på udviklingen i spillets regler.
1: Vi starter med psykologisk flim-flam: "Peg på en af 3 døre". Dette er et formelt ritual uden reelt, empirisk indhold.
2: En nitte bliver nu taget ud af spillet og dit tidligere valg bliver suspenderet - der er nu to døre tilbage. 
Flim-flam slut. Nyt regelsæt. Først nu starter spillet. Først nu er et valg reelt, fordi det nu får empiriske konsekvenser. 
3: 2 døre - og du er stillet frit i.f.t. at vælge den, du pegede på tidligere - eller den anden. 
Hvordan i alverden kan man tro, at dette matematisk adskiller sig fra at spille plat og krone med en ærlig mønt?
Nej, svar ikke - jeg har læst svaret allerede. 
Jargon Blitz kan virke intimiderende, især hvis man bruger sandsynlighedsregning og mange formler - men hvis man ikke starter med korrekte præmisser, så ender det galt - hvilket den indeværende finanskrise er et fint eksempel på.
thread_title:  Monty Hall Problemet og Jargon blitz. 

message: Hvis spilstyreren vælger en ged vil han stadig vinde 2/3 gange ved at vælge om, da der var 66% sandsynlighed for, at han ikke valgte en farrari i første hug. Altså er der 66 % sandsynlighed for, at farrarien er bag en af de to andre døre. Når spilstyreren åbner den ene dør og tilfældigt afslører en ged, så må farrarien sandsynligvis være bag den anden dør.
thread_title:  Fejl i artikel 

message: The explanation given in this section is definitely wrong. It is known as the 'combined doors' solution. Although it is mentioned by several authors, it is also criticized. There is nothing to combine. Door 2 and 3 together have probability 2/3 of hiding the car, just because each door has probability 1/3. Aftewr the opening of door 3 a new situation arises, and it has to be proven that the 'combination' of door 2 and 3 still have together 2/3 chance of hiding the car. Clearly door 3 has in the new situation a chnca 0 on the car, so door 1 and door 2 has combined (!) a chance 1. But it needs some calculation to deduce the separate chances. Madyno (diskussion) 3. jan 2018, 13:06 (CET)
This is a discussion page, what brings you to remove my comment?? Better to tale good notice. Madyno (diskussion) 3. jan 2018, 21:08 (CET)
replies: text: Madyno, matematikken bag dette problem er ganske svær at forstå, fordi den er kontraintuitiv. Men hvis du har kritik, skriv den på dansk. Mener du at fremstillingen har mangler i forhold til engelsk Wikipedia? Artiklerne er mere kortfattede på dansk Wikipedia, men dansk er et lille sprogområde. --Madglad (diskussion) 4. jan 2018, 00:35 (CET)
Well, I am a mathematician and probability theory is my special topic, so don't get the idea I do not understand the problem. The article is not correct, and not in line with the English Wikipedia. I'm not enough familiar with Danish as to write it. But I hope to find a contributor to this article who understands English and mathematics, to discuss the matter. Madyno (diskussion) 4. jan 2018, 10:58 (CET)
replies: text: :Sorry, I'm going through eye surgery right now and not writing English. Jeg er selv matematiker og har diskuteret dette problem med min fætter. Jeg vil prøve at se om han har tid indenfor de næste par uger, men lige nu er jeg mest fokuseret på operationen. --Madglad (diskussion) 4. jan 2018, 11:12 (CET)
No problem, I'll just wait. Madyno (diskussion) 5. jan 2018, 15:35 (CET)
thread_title:  Venn diagram