▁Human ▁particip ant ▁constraints ▁La ws ▁and ▁eth ical ▁consider ations ▁pre clude ▁some ▁carefully ▁designed ▁ ▁experiments ▁with ▁human ▁subjects . ▁ ▁Leg al ▁constraints ▁are ▁dependent ▁on ▁ ▁juris diction . ▁ ▁Con stra ints ▁may ▁involve ▁ ▁institution al ▁review ▁bo ards , ▁informed ▁consent ▁ ▁and ▁confident ial ity ▁affect ing ▁both ▁clin ical ▁( med ical ) ▁tri als ▁and ▁ ▁behavior al ▁and ▁social ▁science ▁experiments . ▁In ▁the ▁field ▁of ▁to xic ology , ▁for ▁example , ▁experiment ation ▁is ▁performed ▁ ▁on ▁labor atory ▁animals ▁with ▁the ▁goal ▁of ▁defining ▁safe ▁expos ure ▁limits ▁ ▁for ▁humans . ▁Bal ancing ▁the ▁constraints ▁are ▁views ▁from ▁the ▁medical ▁field . ▁Regarding ▁the ▁random ization ▁of ▁patients , ▁ ▁"... ▁if ▁no ▁one ▁knows ▁which ▁ther apy ▁is ▁better , ▁there ▁is ▁no ▁eth ical ▁ ▁imper ative ▁to ▁use ▁one ▁ther apy ▁or ▁another ." ▁( p ▁ 3 8 0 ) ▁Regarding ▁ ▁experimental ▁design , ▁"... it ▁is ▁clearly ▁not ▁eth ical ▁to ▁place ▁subjects ▁ ▁at ▁risk ▁to ▁collect ▁data ▁in ▁a ▁poor ly ▁designed ▁study ▁when ▁this ▁situation ▁ ▁can ▁be ▁easily ▁avoided ... ". ▁( p ▁ 3 9 3 ) ▁ ▁See ▁also ▁▁ ▁Ad vers arial ▁collaboration ▁ ▁Bay esian ▁experimental ▁design ▁ ▁Block ▁design ▁ ▁Box – Be hn ken ▁design ▁ ▁Central ▁composite ▁design ▁ ▁C lin ical ▁trial ▁ ▁C lin ical ▁study ▁design ▁ ▁Computer ▁experiment ▁ ▁Control ▁variable ▁ ▁Cont rolling ▁for ▁a ▁variable