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Standard deviation of a sample

Posted By: Sam Pottle
Date: Friday, 29 June 2012, at 6:26 a.m.

In Response To: Bob Koca, ask not for whom the bell tolls (Bill Phipps)

I checked my own last 50, 7 point matches. My PR was 3.8 with a standard deviation of 1.21. If memory serves, that makes the standard deviation of the sample 1.21/(sqrt of 50) or .17. Meaning, I can be 95% confident that my true PR is somewhere between 3.46 and 4.14

I think you're dividing by sqrt(50) twice. If the standard deviation is 1.21, it's 1.21. The 95% confidence interval would then be 1.38 to 6.22.

Fifty matches is really a very small sample.

Messages In This Thread

• Bob Koca, ask not for whom the bell tolls
  Bill Phipps -- Thursday, 28 June 2012, at 12:56 a.m.
  • Bob Koca, ask not for whom the bell tolls
    Timothy Chow -- Thursday, 28 June 2012, at 3:20 p.m.
    • Bob Koca, ask not for whom the bell tolls
      Bob Koca -- Thursday, 28 June 2012, at 4:08 p.m.
      • Bob Koca, ask not for whom the bell tolls
        Matt Cohn-Geier -- Saturday, 30 June 2012, at 12:56 a.m.
        • Bob Koca, ask not for whom the bell tolls
          Casper van der Tak -- Saturday, 30 June 2012, at 8:02 a.m.
    • Bob Koca, ask not for whom the bell tolls
      Bill Phipps -- Thursday, 28 June 2012, at 4:08 p.m.
    • distribution of PR
      Bill -- Friday, 29 June 2012, at 1:55 p.m.
      • distribution of PR
        Timothy Chow -- Friday, 29 June 2012, at 6:06 p.m.
  • Bob Koca, ask not for whom the bell tolls
    Bob Koca -- Thursday, 28 June 2012, at 8:08 p.m.
    • Bob Koca, ask not for whom the bell tolls
      Bill Phipps -- Thursday, 28 June 2012, at 8:29 p.m.
      • Bob Koca, ask not for whom the bell tolls
        Bob Koca -- Thursday, 28 June 2012, at 9:01 p.m.
      • Bob Koca, ask not for whom the bell tolls
        Timothy Chow -- Thursday, 28 June 2012, at 9:31 p.m.
        • Bob Koca, ask not for whom the bell tolls
          Bill Phipps -- Thursday, 28 June 2012, at 11:39 p.m.
          • Bob Koca, ask not for whom the bell tolls
            Timothy Chow -- Friday, 29 June 2012, at 12:36 a.m.
            • Timothy
              Bill Phipps -- Friday, 29 June 2012, at 2:24 a.m.
              • Timothy
                Bob Koca -- Friday, 29 June 2012, at 4:54 a.m.
              • -1
                Casper van der Tak -- Friday, 29 June 2012, at 7:38 a.m.
                • "Chowing" a position
                  Timothy Chow -- Friday, 6 July 2012, at 2:15 p.m.
                  • LOL, I take it all back....
                    Casper van der Tak -- Friday, 6 July 2012, at 3:39 p.m.
                  • And the gunnery sergeant and photographer...
                    higonefive -- Friday, 6 July 2012, at 6:47 p.m.
              • Timothy
                Timothy Chow -- Friday, 29 June 2012, at 5:38 p.m.
                • Timothy
                  Tom Keith -- Friday, 29 June 2012, at 7:11 p.m.
                  • Timothy
                    Timothy Chow -- Friday, 29 June 2012, at 10:34 p.m.
                    • Timothy
                      Matt Cohn-Geier -- Saturday, 30 June 2012, at 12:42 a.m.
                      • Timothy
                        Jason Lee -- Saturday, 30 June 2012, at 1:45 a.m.
                        • Timothy
                          Matt Cohn-Geier -- Saturday, 30 June 2012, at 1:52 a.m.
                          • Timothy
                            Bill Phipps -- Saturday, 30 June 2012, at 2:15 a.m.
                            • Timothy
                              Bob Koca -- Saturday, 30 June 2012, at 5:22 a.m.
                          • An example
                            David Rockwell -- Saturday, 30 June 2012, at 3:01 a.m.
                            • Another example
                              David Rockwell -- Saturday, 30 June 2012, at 3:09 a.m.
                            • An example
                              Matt Cohn-Geier -- Saturday, 30 June 2012, at 3:15 a.m.
                        • Timothy
                          Jake Jacobs -- Saturday, 30 June 2012, at 4:11 a.m.
                      • Timothy
                        Casper van der Tak -- Saturday, 30 June 2012, at 8:28 a.m.
                        • Never so simple... (long)
                          Chuck Bower -- Saturday, 30 June 2012, at 3:27 p.m.
                          • Never so simple... (long)
                            Casper van der Tak -- Saturday, 30 June 2012, at 4:13 p.m.
                            • Never so simple... (long)
                              Chuck Bower -- Saturday, 30 June 2012, at 8:15 p.m.
                              • Never so simple... (long)
                                Casper van der Tak -- Saturday, 30 June 2012, at 8:35 p.m.
                      • Timothy
                        Timothy Chow -- Sunday, 1 July 2012, at 6:53 p.m.
              • Timothy
                rew -- Saturday, 30 June 2012, at 12:03 p.m.
          • Bob Koca, ask not for whom the bell tolls
            Jason Lee -- Friday, 29 June 2012, at 3:41 a.m.
  • Standard deviation of a sample
    Sam Pottle -- Friday, 29 June 2012, at 6:26 a.m.
    • Standard deviation of a sample
      Bob Koca -- Friday, 29 June 2012, at 6:45 a.m.
      • Standard deviation of a sample
        Sam Pottle -- Friday, 29 June 2012, at 7:03 a.m.
        • Standard deviation of a sample
          Bob Koca -- Friday, 29 June 2012, at 7:15 a.m.