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Re: [baseball-databank] Re: Lahman DB and Age Calculation

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  • Tom Stillman
    I have to agree with this. How many people do you know that were born at the end of September/beginning of October (conceived during the Holidays) and how
    Message 1 of 24 , Mar 8, 2007
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      I have to agree with this. How many people do you
      know that were born at the end of September/beginning
      of October (conceived during the Holidays) and how
      many do you know born toward the middle of November
      (conceived on Valentine's Day)?

      Tom Stillman

      --- Douglas Creager <dcreager@...> wrote:

      > > This isn't necessarily related. There is also
      > some evidence (and I may be misquoting) that players
      > with August and Sept birthdays are more likely to
      > make the majors. Here is a percentage for players
      > born since 1960.
      >
      > Doesn't this assume that the birthrates are even
      > throughout the year?
      > It could just be that more kids are born in August
      > and September.
      > You'd probably need to compare those percentages to
      > some census data
      > to make the argument more convincing.
      >
      > cheers
      > --doug
      >
      > --
      > Douglas Creager
      > DPhil Candidate, Computing
      > Oxford University Computing Lab
      > http://www.softeng.ox.ac.uk/people/Douglas.Creager/
      > <douglas.creager@...>
      >




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    • KJOK
      If someone HAS compiled some minor league stats in electronic form, please let me know, as there is a startup project to try to create a minor league database.
      Message 2 of 24 , Mar 8, 2007
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        If someone HAS compiled some minor league stats in electronic form, please let me know, as there is a startup project to try to create a minor league database.
         
        THANKS,
        Kevin

        roca_h@... wrote:
        Sean, do you know of any Minor League database such as Baseball-Reference.
        Many thanks
        regards
        Henri
        >
        .



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      • Michael Westbay
        ... So what you re saying is that this is a cultural issue. I have evidence that this may be correct. +-------+---------+ ... +-------+---------+ ...
        Message 3 of 24 , Mar 8, 2007
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          Sean Forman wrote:

          > This isn't necessarily related. There is also some evidence (and I may be
          > misquoting) that players with August and Sept birthdays are more likely to
          > make the majors. Here is a percentage for players born since 1960.
          > ...
          > The speculation is that the July and June kids have to play up with older
          > kids in little league and the Aug, Sept kids are the oldest kids in the
          > leagues and get more attention as they are more physically developed. Or
          > maybe parents are just lying to keep their kids back a year.

          So what you're saying is that this is a cultural issue. I have evidence
          that this may be correct.

          +-------+---------+
          | Month | Count |
          +-------+---------+
          | 1 | 6.1284 |
          | 2 | 4.4261 |
          | 3 | 5.3502 |
          | 4 | 11.1868 |
          | 5 | 11.3813 |
          | 6 | 10.7490 |
          | 7 | 10.4572 |
          | 8 | 10.0195 |
          | 9 | 8.2685 |
          | 10 | 8.5117 |
          | 11 | 6.3716 |
          | 12 | 7.1498 |
          +-------+---------+

          The above is the percentage of 2056 players in NPB (Nippon Professional
          Baseball) born in or after 1960. Here the peak is in April and May and
          steadily goes down from there. The school year in Japan starts in
          April, so April and May born kids will tend to be the most physically
          developed in their school years.

          (Note: I did not filter out foreign players, but August/September borns
          don't seem to effect the distribution any.)

          This is an interesting study.


          --
          Michael Westbay
          Writer/System Administrator
          http://JapaneseBaseball.com
        • Tangotiger
          -- Sean Forman ... I understand the reason. But if I have 20 players all born between Jan 1, 1980 and Dec 31, 1980, their
          Message 4 of 24 , Mar 8, 2007
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            -- Sean Forman <sean-forman@...>
            wrote:

            > Tango,
            >
            > There is actually a reasonable reason for using July
            > 1st as the cutoff.
            > When you do that the player's age is given as the
            > age they played most of
            > the year as since July 1st is just about the halfway
            > point of the season. A
            >

            I understand the reason. But if I have 20 players all
            born between Jan 1, 1980 and Dec 31, 1980, their age,
            as of July 1, 2007, will be between 26.5 and 27.5.
            Their average age is therefore 27.0.

            However, if you use the July 1, 2007 Bill James method
            as the cutoff, the players aged "27" will be born
            between July 2, 1979 and July 1, 1980. Those guys are
            aged 27.00 to 27.99, for an average age of 27.5.

            Therefore, if you were to list a group of 20 players
            aged "27" using the Bill James method, they in fact
            are aged, as a group 27.5 years old.

            Except for "age", there is no other number that
            society would floor. All other conventional numbers
            are rounded.

            If there were no such thing as a word called "age",
            season minus birth year is perfectly acceptable. It
            is simply because we treat an age of 27.99 as "27" are
            we having even having this discussion.

            Tom




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            http://www.InsideTheBook.com
            The Book--Playing The Percentages In Baseball











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          • Michael Westbay
            I ve also run this query through my Taiwanese database (combined CPBL and TML players). Out of 1,700 players, these are the results: Month Count 1 8.6%
            Message 5 of 24 , Mar 8, 2007
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              I've also run this query through my Taiwanese database (combined CPBL
              and TML players). Out of 1,700 players, these are the results:

              Month Count
              1 8.6%
              2 7.4%
              3 7.6%
              4 6.8%
              5 7.0%
              6 5.7%
              7 5.4%
              8 8.8%
              9 10.1%
              10 11.6%
              11 12.0%
              12 9.1%

              If I had to make a guess, I'd say that the school year starts around the
              end of August, beginning of September in Taiwan, making those born in
              the August to November range the biggest in their classes. Notice how
              the numbers drop steadily starting in December?

              Wow. This is interesting.

              --
              Michael Westbay
              Writer/System Administrator
              http://JapaneseBaseball.com
            • Tangotiger
              ... There was a thread about this on a Freakanomics blog entry. If you are going to calculate age as a single integer, it needs to be done by looking at where
              Message 6 of 24 , Mar 8, 2007
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                --- Michael Westbay
                <westbaystars@...> wrote:

                >
                > Wow. This is interesting.
                >


                There was a thread about this on a Freakanomics blog
                entry.

                If you are going to calculate age as a single integer,
                it needs to be done by looking at where the players
                are clustered, whether by when they are born, when
                they are drafted, or when they enter school.

                "Mid-point of season, and flooring the age" is
                meaningless. If you choose a meaningless arbitrary
                point, make the calculation the easiest.

                Tom


                ---------------------------------------------
                http://www.InsideTheBook.com
                The Book--Playing The Percentages In Baseball











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              • Tangotiger
                Here s one such article: http://www.nytimes.com/2006/05/07/magazine/07wwln_freak.html?ei=5070&en=1ff54422d3371507&ex=1173502800&pagewanted=all Tom ...
                Message 7 of 24 , Mar 8, 2007
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                  Here's one such article:
                  http://www.nytimes.com/2006/05/07/magazine/07wwln_freak.html?ei=5070&en=1ff54422d3371507&ex=1173502800&pagewanted=all

                  Tom

                  ---------------------------------------------
                  http://www.InsideTheBook.com
                  The Book--Playing The Percentages In Baseball











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