# left handed probabilities

Document Sample

```					Keith Milsom 8/30/2012                                                        of 2
Page 1a9537fd6-429b-44d8-bdc3-df033cf0b98e.xls / Left handed child probabilities

WHAT IS THE CHANCE OF HAVING A LEFT-HANDED CHILD?
This worksheet was created by Keith Milsom, owner of Anything Left-Handed as part of an article on the probability
of various left-right parent mixes having a left-handed child

You can see the article here
http://www.anythingleft-handed.co.uk/lefty-probability.html

And you can see the Anything Left-handed survey results here
http://www.lefthandersday.com/lefthanded_surveyresults.html

This is only a layman's analysis and if you can improve on it, please let me know
email       keith@anythingleft-handed.co.uk

Starting number of individuals                                         1,000,000
Starting number of couples                                               500,000
Assumed starting rate of left-handedness in the population                   10%

Percentage chances of having a left-handed child for each possible parent combination
Percent of                    % chance                       % of LH                        % of RH
all couples     Number of           of LH    Number of        children      Number of        children
Father    Mother           with mix       Couples           child LH children         with mix     RH children       with mix

Left       Left                    1%          5,000          20.0%        1,000           2.0%          4,000          0.9%
Left       Right                   9%         45,000          12.0%        5,400          10.8%         39,600          8.8%
Right      Left                    9%         45,000          16.0%        7,200          14.4%         37,800          8.4%
Right      Right                  81%        405,000           9.0%       36,450          72.8%        368,550         81.9%

100%         500,000                      50,050         100.0%        449,950        100.0%

Resulting percentage of left-handed children                                10.0%

Percentage of all children born to two right-handed parents who are left-handed            9.0%
Keith Milsom 8/30/2012                               of 2
Page 2a9537fd6-429b-44d8-bdc3-df033cf0b98e.xls / Left handed child probabilities

Total
Children    Keith    ALH    McManus     Coren

5,000    20.0%   14.0%     26.1%     35.0%
45,000    13.0%   13.0%     19.5%     10.0%
45,000    13.0%   13.0%     19.5%     20.0%
405,000     9.3%    9.3%      9.5%     10.0%

500,000

```
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
 views: 10 posted: 8/30/2012 language: English pages: 2
How are you planning on using Docstoc?