Calculation of odds: probability and deviation

[sfairbrother243]

*WARNING* My understanding of maths is pretty limited and i don't know if i am being really stupid or not.

Ive been looking into data analysis of football matches, working out proabilities of certain situations happening and how steady the averages are. i come across a website which as really helped me understand some of these concepts. But 2 calculations have left me stumped and i don't know if it is me being stupid or the author getting something wrong?

the author had gone through all matches in prem league from 2005/10 showing % of home, draws and away wins. she then worked out the means for these, then went into the relative and absolute deviation then ended with using this data to obtain the minimum and maximum odds:

The formula for the computation of odds is as follows:
Home win: 48.16% probability results in a price of 2.08 (1 divided by 48.16%)

The minimum odds are computed as follows:
Home win: 2.08 calculated odds multiplied by (1 minus ‘error’(relative deviation) 4.14%) = 1.99

The maximum odds are computed as follows:
Home win: 2.08 calculated odds multiplied by (1 plus ‘error’(relative deviation) 4.14%) = 2.17

am i being very stupid as to why i can't get 1.99 and 2.17 as my answers?

many thanks guys!

 

[Opalg]

*WARNING* My understanding of maths is pretty limited and i don't know if i am being really stupid or not.

Ive been looking into data analysis of football matches, working out proabilities of certain situations happening and how steady the averages are. i come across a website which as really helped me understand some of these concepts. But 2 calculations have left me stumped and i don't know if it is me being stupid or the author getting something wrong?

the author had gone through all matches in prem league from 2005/10 showing % of home, draws and away wins. she then worked out the means for these, then went into the relative and absolute deviation then ended with using this data to obtain the minimum and maximum odds:

The formula for the computation of odds is as follows:
Home win: 48.16% probability results in a price of 2.08 (1 divided by 48.16%)

The minimum odds are computed as follows:
Home win: 2.08 calculated odds multiplied by (1 minus ‘error’(relative deviation) 4.14%) = 1.99

The maximum odds are computed as follows:
Home win: 2.08 calculated odds multiplied by (1 plus ‘error’(relative deviation) 4.14%) = 2.17

am i being very stupid as to why i can't get 1.99 and 2.17 as my answers?

many thanks guys!

What you have to remember here is that a percentage is measured on a scale from 0 to 100, whereas a probability is measured on a scale from 0 to 1. What that means is that to convert a percentage of 4.14% to a probability you have to divide it by 100, getting 0.0414. The formula for "minimum odds" say that you need to subtract this probability from 1 (getting 0.9586) and then multiply that by 2.08. That gives the answer 1.99 (to two decimal places). The calculation for the "maximum odds" will be similar.