Sinclair Coefficients

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The Sinclair Coefficient (S.C.) There are eight bodyweight categories in Olympic Weightlifting for male athletes: 56kg, 62kg, 69kg, 77kg, 85kg, 94kg, 105kg, +105kg, and seven for female athletes: 48kg, 53kg, 58kg, 63kg, 69kg, 75kg, +75kg. Also, there are two events (two types of lifts): - The Snatch, and The Clean and Jerk. However, at the championships, medals are presented in both lifts separately, and in Total (the combined result of the best Snatch and the best Clean and Jerk). To compare and rank the results, especially between bodyweight categories, International Weightlifting Organization uses The Sinclair Coefficient (S.C.) which is derived statistically and calculated for one Olympic cycle (for four years, starting in the Spring of each Olympic year). Total from each bodyweight category is compared as a projection of what would be the Total for that weightlifter if he/she were a competitor in the heaviest bodyweight category with the same level of ability. It is done in four body weight categories for the males (56kg, 69kg, 77kg, +105kg). For the other four categories (62kg, 85kg, 94kg, 105kg) Sinclair Total represents The World Standard (W.S.) because nobody (as of today, 03/18/2008) set the world record (nobody lifted predicted -W.S.-Total). Those projections (Sinclair Total) are shown below. The Sinclair Coefficient (S.C.) is 10 raised to the exponent A times X squared if his/her bodyweight of x kg is less than or equal to b kg (where X equals the logarithm to the base 10 of the ratio of x to b), and is equal to 1 if his/her bodyweight of x kg exceeds b kg. A= Coefficient for this Olympic cycle: - For males A= 0.845716976 - For females A= 1.316081431 x= weightlifter’s bodyweight in kilograms (kg) ( 1kg = 2.2046 lbs, 1lb = 0.453592kg) b= world record holder’s body weight in kg (in the heaviest category, +105kg for males, and +75kg for females): - For males = 168.091kg - For females = 107.844kg X= log10(x/b) AX2= Exponent To explain this formula, imagine a weightlifter weighing 56 kilograms (123.45 pounds) has a Total (combined results of The Snatch and The Clean and Jerk) of 305 kg. A=0.845716976 X=log10(56/168.091) = -0.477356434 AX2=0.192712821 S.C.=10AX2 = 10 0.1927122821 = 1.558521584 Sinclair Total = Actual Total X S.C. Sinclair Total = 305 kg X 1.558521584 = 475.349kg (475.349083kg ) To understand the whole idea, here is the chart with all male bodyweight categories (in kg) and its world record Totals (W.R.), World Standards (W.S.), Sinclair Coefficients (S.C.), Sinclair Total (S.T.). By looking at the S.T. we determined the RANK.

  kg     W.R.          S.C.               S.T.                         RANK
  56      305       1.558521584         475.349083                      3
  62      326       1.441035030         469.7773733                     7
  69      357       1.338020780         477.6734183                     1
  77      377       1.250896723         471.5880646                     6
  85     395WS      1.186208968         468.5525422                     8
  94     417WS      1.132098286         472.0849853                     4
 105     440WS      1.084720914         477.2772023                     2
+105      472       1.000000000         472.0000000                     5               

The same is done for the seven female body weight categories.