THE  SCOPE  OF  PSYCHOLOGICAL  TESTS  I9I
A  second  impediment  in  the  way  of  selecting  big  men
by  tests  is  the  necessity  of  trying  out  preliminary  tests
on  a  large  group  of  individuals  all  doing  exactly  the  same
kind  of  work.  Unless  tests  are  tried  on  a  large  scale,  the
probable  errors  are  likely  to  make  the  results  worthless;
and  unless  all  the  individuals  involved  are  doing  the  same
kind  of  work,  it  is  impossible  to  compare  their  relative
ability  as  workers  with  their  relative  ability  in  the  various
tests.  In  the  experiments  described  here,  there  were
generally  twenty  or  more  subjects  in  each  group.  And
m  most  cases,  the  members  of  the  various  groups  were
engaged  in  exactly  the  same  kind  of  work.  This  condition
is  very  common  in  factories,  where  quantity  production
and  the  fine  division  of  labor  have  made  it  necessary  for
huge  groups  of  individuals  to  engage  in  the  same  process
°f  production.  However,  the  higher  we  go  in  the  scale
°f  work,  the  more  difficult  it  is  to  find  this  condition.
Very  few  men  in  important  positions  are  engaged  in  tasks
tvhich  are  exactly  the  same,  and  therefore,  it  is  almost
impossible  to  compare  them  with  each  other  so  as  to  obtain ­
  a  record  of  their  relative  abilities.  Even  where  the
names  of  a  number  of  positions  are  alike,  it  by  no  means
follows  that  the  tasks  performed  are  also  alike.  No  one
is  more  familiar  with  this  condition  than  the  employment
manager  whose  duty  it  is  to  secure  men  for  a  large  number
°f  important  positions  alike  in  name  but  very  different
m  fact.
Finally,  even  if  the  members  of  a  group  are  engaged  in
the  same  kind  of  work,  it  is  essential  that  the  work  be  of
s uch  a  nature  as  to  furnish  an  objective  measure  of  production. ­
  By  an  objective  measure  of  production  is
lUeant  simply  an  impersonal  record  of  the  amount  and
Quality  of  work  done  by  each  individual.  We  have  seen