﻿Laws 
  of 
  Fluctuations 
  737 
  

  

  the 
  case 
  of 
  symmetrical 
  curves, 
  perhaps 
  in 
  two 
  

   figures. 
  

  

  Also 
  in 
  comparing 
  different 
  curves 
  with 
  one 
  

   another, 
  the 
  quartiles 
  are 
  of 
  great 
  importance. 
  

   Whenever 
  an 
  empirical 
  fluctuation-curve 
  is 
  to 
  be 
  

   compared 
  with 
  the 
  theoretical 
  form, 
  or 
  when 
  

   two 
  or 
  more 
  cases 
  of 
  variability 
  are 
  to 
  be 
  con- 
  

   sidered 
  under 
  one 
  head, 
  the 
  lines 
  are 
  to 
  be 
  

   drawn 
  on 
  the 
  same 
  base. 
  It 
  is 
  manifest 
  that 
  

   the 
  averages 
  must 
  be 
  brought 
  upon 
  the 
  same 
  

   ordinate, 
  but 
  as 
  to 
  the 
  steepness 
  of 
  the 
  line, 
  

   much 
  depends 
  on 
  the 
  manner 
  of 
  plotting. 
  Here 
  

   we 
  must 
  remember 
  that 
  the 
  mutual 
  distance 
  of 
  

   the 
  ordinates 
  has 
  been 
  a 
  wholly 
  arbitrary 
  

   one 
  in 
  all 
  our 
  previous 
  considerations. 
  And 
  

   so 
  it 
  is, 
  as 
  long 
  as 
  only 
  one 
  curve 
  is 
  considered 
  

   at 
  a 
  time. 
  But 
  as 
  soon 
  as 
  two 
  are 
  to 
  be 
  com- 
  

   pared, 
  it 
  is 
  obvious 
  that 
  free 
  choice 
  is 
  no 
  longer 
  

   allowed. 
  The 
  comparison 
  must 
  be 
  made 
  

   on 
  a 
  common 
  basis, 
  and 
  to 
  this 
  effect 
  the 
  quar- 
  

   tiles 
  must 
  be 
  brought 
  together. 
  They 
  are 
  to 
  lie 
  

   on 
  the 
  same 
  ordinates. 
  If 
  this 
  is 
  done, 
  each 
  

   division 
  of 
  the 
  base 
  corresponds 
  to 
  the 
  same 
  

   proportionate 
  number 
  of 
  individuals, 
  and 
  a 
  

   complete 
  comparison 
  is 
  made 
  possible. 
  

  

  On 
  the 
  ground 
  of 
  such 
  a 
  comparison 
  we 
  may 
  

   thus 
  assert 
  that 
  fluctuations, 
  however 
  different 
  

   the 
  organs 
  or 
  qualities 
  observed, 
  are 
  the 
  same 
  

   whenever 
  their 
  curves 
  are 
  seen 
  to 
  overlap 
  one 
  

  

  