Oregon Scientific GR101

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Product information:
 
Product information:
 +
 
http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html
 
http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html
  
 
Manual:
 
Manual:
 +
 
http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf
 
http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf
 +
 +
Research:
 +
 +
<source lang="text">
 +
 +
 +
Hacking the GR101 revisited (see [0]) or:
 +
How to convert the raw impedance reading from a GR101 to percentage body fat and percentage body water - by Ap15e
 +
 +
 +
Definitions:
 +
 +
raw_impedance: data from RFXtrx
 +
BD          : Body Density [kg/m^3]
 +
FFM          : Fat Free Mass [kg]
 +
Wt          : Weight [kg]
 +
Ht          : Height [cm]
 +
Z            : Impedance [ohm]
 +
%fat        : percentage body fat [%]
 +
%water      : percentage body water [%]
 +
 +
 +
Constants (best fit to formulas for data from a spreadsheet publicly available, see [1])
 +
 +
impedance_factor = 39.198
 +
hydration        = 0.728895
 +
 +
 +
Formulas for males and females
 +
Z = raw_impedance / impedance_factor
 +
 +
%water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100
 +
 +
 +
Formulas for males
 +
 +
BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]]
 +
 +
%fat = ( 4.57 / BD - 4.142 ) x 100                  [Brozek, see [3]]
 +
 +
Additional formulas for percent body fat:
 +
 +
%fat = ( 4.95  / BD - 4.5  ) x 100                  [Siri, see [3]]
 +
%fat = ( 4.374 / BD - 3.928 ) x 100                  [Schutte; for African-Americans, see [3]]
 +
%fat = ( 4.86  / BD – 4.39  ) x 100                  [Wagner]
 +
 +
 +
Formulas for females
 +
 +
FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt    [Tanita Corporation, see [2]]
 +
 +
%fat = ( Wt - FFM ) / Wt x 100
 +
 +
 +
Notes
 +
 +
The formulas for males (Brozek) match the values on the remote display to a high degree
 +
(error is < 0.5% for %fat and < 0.3% for %water for the data from the spreadsheet).
 +
 +
The formulas for females yield higher errors. There is insufficient data in the spreadsheet
 +
for further analysis.
 +
 +
 +
References
 +
 +
[0] http://www.fabienletort.com/blog/2008/domotic-help-us-hack-the-gr101.html
 +
 +
[1] http://spreadsheets.google.com/ccc?key=pQy-b-0ho4QdU4ecNy0TLLg&hl=fr
 +
 +
[2] Jebb SA, Cole TJ, Doman D, Murgatroyd PR, Prentice AM.
 +
    Evaluation of the novel Tanita body-fat analyser to measure body composition by comparison with a four-compartment model.
 +
    Br J Nutr. 2000 Feb;83(2):115-22.
 +
    PMID:10743490
 +
    Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10743490
 +
    Full text: http://journals.cambridge.org/abstract_S0007114500000155
 +
    NOTE: The unit of measure for the height in the formula for body density is cm, not m.
 +
 +
[3] The Process of Physical Fitness Standards Development
 +
    Full text: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA495349
 +
</source>
 +
  
 
Requirements:
 
Requirements:
 +
 
tbc
 
tbc
  
 
Downloads:
 
Downloads:
 +
 
tba
 
tba
  
 
Installation:
 
Installation:
 +
 +
tbd
  
 
Further reading:
 
Further reading:
 +
 
tbc
 
tbc

Revision as of 17:58, 30 September 2012

Product information:

http://au.oregonscientific.com/cat-Sports-and-Health-sub-Body-Weight-Scales-prod-Digital-Scale-with-Body-Mass-Index-and-Remote-Display-unit.html

Manual:

http://au.oregonscientific.com/ulimages/manuals2/GR101.pdf

Research: 

 Hacking the GR101 revisited (see [0]) or: 
 How to convert the raw impedance reading from a GR101 to percentage body fat and percentage body water - by Ap15e
 
 
 Definitions:
 
 raw_impedance: data from RFXtrx
 BD           : Body Density [kg/m^3]
 FFM          : Fat Free Mass [kg]
 Wt           : Weight [kg]
 Ht           : Height [cm]
 Z            : Impedance [ohm]
 %fat         : percentage body fat [%]
 %water       : percentage body water [%]
 
 
 Constants (best fit to formulas for data from a spreadsheet publicly available, see [1])
 
 impedance_factor = 39.198
 hydration        = 0.728895
 
 
 Formulas for males and females
 Z = raw_impedance / impedance_factor
 
 %water = ( Wt - %fat / 100 x Wt ) x hydration / Wt x 100
 
 
 Formulas for males
 
 BD = 1.100696 - 0.107903 x Wt x Z/Ht^2 + 0.00017 x Z [Tanita Corporation, see [2]]
 
 %fat = ( 4.57 / BD - 4.142 ) x 100                   [Brozek, see [3]]
 
 Additional formulas for percent body fat:
 
 %fat = ( 4.95  / BD - 4.5   ) x 100                  [Siri, see [3]]
 %fat = ( 4.374 / BD - 3.928 ) x 100                  [Schutte; for African-Americans, see [3]]
 %fat = ( 4.86  / BD – 4.39  ) x 100                  [Wagner]
 
 
 Formulas for females
 
 FFM = 13.96674 + 0.348613 x Ht^2/Z + 0.168998 x Wt    [Tanita Corporation, see [2]]
 
 %fat = ( Wt - FFM ) / Wt x 100
 
 
 Notes
 
 The formulas for males (Brozek) match the values on the remote display to a high degree 
 (error is < 0.5% for %fat and < 0.3% for %water for the data from the spreadsheet).
 
 The formulas for females yield higher errors. There is insufficient data in the spreadsheet 
 for further analysis.
 
 
 References
 
 [0] http://www.fabienletort.com/blog/2008/domotic-help-us-hack-the-gr101.html
 
 [1] http://spreadsheets.google.com/ccc?key=pQy-b-0ho4QdU4ecNy0TLLg&hl=fr
 
 [2] Jebb SA, Cole TJ, Doman D, Murgatroyd PR, Prentice AM.
     Evaluation of the novel Tanita body-fat analyser to measure body composition by comparison with a four-compartment model.
     Br J Nutr. 2000 Feb;83(2):115-22.
     PMID:10743490
     Abstract: http://www.ncbi.nlm.nih.gov/pubmed/10743490
     Full text: http://journals.cambridge.org/abstract_S0007114500000155
     NOTE: The unit of measure for the height in the formula for body density is cm, not m.
 
 [3] The Process of Physical Fitness Standards Development 
     Full text: http://www.dtic.mil/cgi-bin/GetTRDoc?AD=ADA495349


Requirements:

tbc

Downloads:

tba

Installation:

tbd

Further reading:

tbc

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