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    Can we trust betting company on the odds they publish?

    It's WorldCup time, and we care about each team's outright odds.
    There are lots of betting companies on net.
    And they publishes their views of odds.
    For example:
    Argentina vs Brazil. Odd is 4:1.2.
    That means if you bet 1 dollar on Argentina and if it wins, you'll earn 4 dollar back, and for Brazil you'll earn 1.2 dollar back.
    For a company to make money you have to make sure the sum of probabilities (reciprocals of odds) are above 1, in our example it's,say, 1/4 + 1/1.2. That means the company think Argentina has 25% chance of winning while Brazil has 83% chance. The total 107% minus 1 is 7%, that's what we usually called the profit space for betting company.


    Ok. Now comes the problem. If betting company say Brazil will win at 83%, shall we trust it? Betting company makes money on these odds, and they have to be accurate, if they say Brazil win at 10% and all the people bet on it, the company will lose a huge if Brazil actually wins. Actually, estimating probability is key to make money for betting company.

    Let's assume winning probability of Argentina is A, and for Brazil is B, where A+B>1. And m shares are bet on A and n shares on B. And the actual winning chance of Brazil is x.
    In order to make money, betting company has to make sure (1-x)(m+n-m/A)+x(m+n-n/B)>0.
    this is eternally true when B>x>1-A,
    that means if betting company can assure its publishes probability of Brazil is just above actual x and its probability of Agentina is just above 1-x, they can always make money no matter which team wins out.
    So we can always trust betting companies since they make a living on giveing accurate A and B.

    Wait...real game is not x. It's 1 and 0. Do you think betting companies count on accurate x to make money? I don't think so. Even you have the most accurate A and B, you can still lose money. Let's see here: A=25%, B=83%, m=100, n=100. If Argentina wins, the company will lose 200 dollars. You know Brazil has a bigger chance of winning, but as a betting company, you don't bet. You don't want to lose money no matter which team wins. So the real way to make sure win is that:
    B/(1-B)>n/m>(1-A)/A -----------(*)
    If they can control the ratio of n and m right between the numbers above. They can always make money no matter what x is between 0 and 1. Always.
    So this is the real thing: Controlling shares bet on each team.
    If too many people bet on A, that is to say m is big, thus n/m is relatively small, betting company will lower B and increase A; and vice versa in order to make sure n/m is within the scope.
    That's why you can see different odds on different companies pages -- they have different ratio of people betting on it.
    Of course, things are not so easy after all. And a combined model including x is acctually used. That is to say, if betting company can assure x is within a certain scope (like x>0.5), they can have a even bigger scope for n/m to fit into.
    For x>0.5, the (*) can turn to B/(1-B)>n/m>(1/A-2)/(2-1/B),
    which is easier to for them to control n/m.

    So in my point of view, you can't trust it. You can take it as reference, but you don't know the actually ratio of people bet on each team, thus you don't know how much the betting company changed the odds from "real" one. Remember, their aim is making sure to make money, not providing accurate odds and winning applauds.

    Top 10 trader :P

    Google       Hello, guzhilong!     Cash: $6,044.79   Securities: $2,453.04    Rank:   7 out of 1746





    There is an internal virtual stock market inside google, and googlers love these bids and asks. After one month of effort, I squeezed myself into top 10. It's fun being a so-called trader...

    Movement

    1 J&J buys Pfizer's consumer unit for $16.6bn
    2 Buffett giving fortune away (to Gates Foundation)
      (he gave most of his money to the foundation of his friend, Bill Gates, instead of creating his own in his own image)
    3 GOOG stock above 400 again
    4 Value your home in Zillow.com
    5 Mittal finally merged Arcelor, now turning to the world's largest steelmaker by turnover as well as volume, controlling 10% of the world's steel output. Bill Gates' number one rich, Buffett's second, you know who's the fifth? Mittal, the chairman of Mittal. And he's an indian.

    RIOT

    Huge student riot in Zheng*Zhou...
    They smashed everything they saw...

    WAAAAAADE!

    Say that loud!

    MIAMI HEAT

    My heart is at your hand.
    MUST WIN!!!

    (btw i bet a lot of $ on it....)

    joyful day

    Saw the movie of 9# cup final made by longmao on my laptop, which is quite moving, saw Van Wilder, my favorite movie, again while doing gym for 1.5 hour, met a new friend Jason while having dinner, wrote letter to friends and sent several gtalk invite, had delicious meal, had a shower while having my clothes washed, now start coding. you can't expect more than this...

    football ranking

    FIFA ranking is really aweful...
    USA ranks 5th and lots of other counties are messed up.
    And the Spearman correlation coefficient of this rank and betting company's (which is more likely) is 0.69!!!
    But FIFA said they're going to publish the new ranking system right after this world cup....

    Here's the best ranking site i've ever seen:
    http://www.eloratings.net/
    Enjoy.

    las vegas

    my boss went to las vegas last weekend...and back today saying: it's horribly hot there, they simply don't want you to go outside now i see why they want it built in desert.

    pathetic Monster

    due to illegal option granting to top guys, Monster Inc suffered severe loss on stock last week.... -8%..-7%...-5%...

    Blog search

    Here are some excellent blog search engines:
    1 Icerocket.com
    2 BlogSearchEngine.com
    3 Search.Eponym.com
    4 Blogsearch.google.com

    Actually I don't like the idea of searching(peeping) other's diary. But as long as stuff like baidu claims "not responsible for illegal contents because we only provide links", I'm ok with my sin.

    Compete for the Worst

    There are a bunch of ppl who wanna compete for the worst. Here's some of them:
    1 Chinese football team. Yesterday they lose 1-3 to France, and they made one important French player seriously injured...I think "good for nothing" is not enough to describe this team...
    2 CHEN Shuibian. For those corruptions from his family, now the Chinese Nationalist Party decided to impeach him yesterday. Sometimes we admire DENG Xiaoping for what he said, "just wait and see", and they'll collapse themselves.

    造词成功:)

    哈哈 终于创造了搜索引擎仅能搜到一个网页的关键词。
    就是我的space的副标题:
     
    Izoryx
     
    发音是 /i'Zoriks/。 这个词没有虾米意思,呵呵,就是觉得好玩。
    大家可以用googleicerocket试试,baidu和yahoo暂时还没有收录。
     
    以后大家定位我的space只要输入这个词就可以了,
    全世界唯一。
     
     
    PS:当我在玩这个无聊的游戏的时候,看看19岁的美国哥们做了些什么吧,
    一个百万资产的公司的总裁。

    The Mavs Can’t ? -- by Mark Cuban

    The Mavs CAN’T play Defense.
    The Mavs CAN’T play a half court game.
    The Mavs CAN’T get past the first round
    The Mavs CAN’T beat <fill in a team here > because <fill in an excuse here>
    Dirk CAN’T  play against smaller defenders
    Dirk CAN’T take the ball to the basket
    Dirk CAN’T play defense
    Dirk CAN’T step up in the playoffs
    Stack CAN’T play a team game
    JET CAN’T be the point guard on a Finals team
    Devin Harris CAN’T get past last years playoffs to have an impact
    Gana Diop CAN’T be a player in this league
    Avery Johnson CAN’T lead this team to the Finals as a 1st year coach

    Thank you. Thank you to everyone who has ever said or written about what they think the Mavs cant do.  It was motivation that Avery called on early and often.

    There is an old saying, Those who can, do. Those who can’t, are usually commentators telling as many people as will read, watch or listen why they think someone else who is actually trying to accomplish something, can’t. 

    No where is this more true than the sportsworld.

    Hats off to the Suns for getting further than anyone ever expected. 
    Hats off to the Suns and the city of Phoenix for being great hosts.

    A huge thank you to Mavs fans around the world. We thank you for wearing your lucky cowboy boots, lucky underwear, lucky hats, tshirts, shorts and pants, for wearing your Mavs gear under your clothes to work and with pride to school and around town.

    A huge thank you to Mavs fans who were jumping up and down, screaming, hugging everyone you could find  and generally going crazy as the clock ran down last night. We heard you. We felt you. All of us on the sidelines felt the exact same way. 

    My heart was pounding so hard, I was almost afraid to move. I have all these little good luck idiosyncrazies (my new word), and i refused to not do them until the clock ran out. I kept on playing mind games with myself. You know… McGrady scored 13 against the Spurs in 33 seconds. Dont relax. Then the ever popular…If we hit this shot, its over… Ok, maybe not. If we get this stop, its over.. Ok maybe not..

    When we hit 00:00, I walked over to where the Suns owners were to thank and congratulate them, and to also make sure I had my legs underneath me. After that, I was never so happy to hug so many sweaty grown men in my entire life.

    The guys who heard cant, but never believed it.

    Four more wins to go.

    The Heat is a great team. Shaq alone has more finals experience than our entire roster. Riley has probably coached more playoffs games than AJ has games. It wont matter. Its going to be a war. Probably no less thrilling and down to the wire as almost every other NBA playoffs series has been.

    We may be the underdogs, but we believe and we dont understand the word can’t.

    MIAMI HEAT

    To the NBA Finals!

    Congratulation to --
    Godfather Don Vito Corleone: Pat Riley
    Actor, Singer and Philanthropist: Shaq
    If I were a girl I would marry: D. Wade
    A Man: A. Mourning
    Future NBA famous commentator: G. Payton
    Even he can shoot; nothing is impossible: A. Walker
    They loved basketball coz: J. Williams

    Wish you a great fight with Dallas/Phoenix.

    Some nice entries

    This is business:
    2006 of Venture Capital in China

    This is success:
    long gratitude letter

    This is lovely life:
    mobile out of use

    This is a poem to the past:
    Untitled

    This is a wrong way:
    地下鐵

    NBA Quotes

    "I have one thing to say to those non-believers. Don't ever underestimate the heart of a champion."
    -- Rudy Tomjanovich

    "It's just God disguised as Michael Jordan."
    -- Larry Bird

    "Nobody roots for Goliath."
    -- Wilt Chamberlain

    "Shooting is of relatively little importance in a player's overall game."
    -- Bill Russell