!"#$%&'$()*+,&
-./)0+1)& 2$()*+,&
!"#$%&$&%'%(()'*(&+,(--")'"./",$0"&+#'$#'1&'1,+
2 3(4'*1&&(+'/(##$5-6'-"1,&'"7",6+8$&%'$&'(&"'*-1##9'
:()16 ;#'%(1-<
2 :"1*8'6(4'+8"'7",6'51#$*#'(='"./",$0"&+')"#$%&
2 >1?"'6(4'1@1,"'(='+8$&%#'6(4'&"")'+('+8$&?'15(4+
2 A$7"'6(4'1'#+1,+$&%'/($&+'=(,'=$%4,$&%'(4+'8(@'+(')('+8$#'$='$+'$#'
#(0"+8$&%'6(4'&"")'$&'+8"'=4+4,"
34% 2$5+&'*$67$8 6& 20699)'$ ) ./)0+1)& 2*$
1+,4 2$: 6;$< %& 2$2 6$'6$+&$!"#=
34:$> 624)0$<+24$ ) ./)0 +1)& 2$')* +,&=
:('"#+15-$#8'#+,(&%'"7$)"&*"'-$&?$&%'01&$/4-1+")'treatments
+('*81&%"#'$&'(&"'(,'0(,"'outcomesB
:(')"+",0$&"'causation.
2 C81&%"#'+('.'*14#"'*81&%"#'+('6'$&'+8$#'0"1#4,15-"'@16B
D
?:/)*$67$!"#$* 2;'+)*
Descriptive0investigations0=(*4#'(&'*(&#+,4*+$&%'1&'1**4,1+"'
)"#*,$/+$(&'(='@81+'$#'81//"&$&%B'
Relational0investigations0"&15-"'+8"',"#"1,*8",'+('$)"&+$=6'
,"-1+$(&#'E*(,,"-1+$(&#F'5"+@""&'04-+$/-"'=1*+(,#B'G(@"7",H'
,"-1+$(&1-'#+4)$"#'*1&',1,"-6')"+",0$&"'+8"'*14#1-'
,"-1+$(&#8$/'5"+@""&'04-+$/-"'=1*+(,#B
Experimental0research01--(@#'+8"'"#+15-$#80"&+'(='1'causal0
relationshipB'I#41--6'+8"#"'1,"'*(&+,(--") '"./",$0"&+#B'
!:/624)*)*
J&'"./",$0"&+'&(,01--6'#+1,+#'@$+8'1'86/(+8"#$#B'
J'86/(+8"#$#'$#'1'/,"*$#"'/,(5-"0'#+1+"0"&+'+81+'*1&'5"'
)$,"*+-6'+"#+")'+8,(4%8'1&'"0/$,$*1-'$&7"#+$%1+$(&B'
C(0/1,")'@$+8'1'+8"(,6H'1'86/(+8"#$#'$#'1'#01--",H'0(,"'
=(*4#")'#+1+"0"&+'+81+'*1&'5"'".10$&")'56'1'#$&%-"'
"./",$0"&+B
!"#$%&'()*+,')-./)0-123#&)4'567#18)-9):#92'1)#;8)$71')
#<<31#2')2,#;)2,')=;817-8)0-123#&)4'567#18>?
@;99$4:/624)*+*
K4--'86/(+8"#$#<'+6/$*1--6'#+1+"#'+81+'+8"," '$#'&(')$==","&*"'
5"+@""&'"./",$0"&+1-'+,"1+0"&+#B'
2 '>@>A)+,'1')#1');7)8'2'<2#6&')8-:: '1';<'9)-;)2,')9%''8)71)
#<<31#<5)7:)2,')-./)4'567#18)#;8)2,')=;817-8)4'567#18>
:8"'%(1-'(='1&'"./",$0"&+'$#'+('=$& ) '#+1+$#+$*1-'"7$)"&*"'+('
*(&=$,0'(,',"L" *+'&4--'86/(+8"#"#'$&'1',"-$15-"'=1#8 $(&B
J'86/(+8"#$#'#8(4-)'#/"*$=6'+8"'$&)"/"&)" &+'71,$15-"#'1&)'
)"/"&)"&+'71,$15-"#B
#&')/)&')& 2$A%0+%>9 )*
M&)"/"&)"&+'71,$15-"#'EMNF<'+8"'=1*+ (,#'+81+'+8"',"#"1,*8",#'1,"'
$&+","#+")'$&'#+4)6$&%'(,'+8"'/(##$5-"'O*14#"P'(='+8"'*81&%"B'
2 MN'$#'$&)"/"&)"&+'(='1'/1,+$*$/1&+;#'5"817$(,B'
2 MN'$#'4#41--6'+8"'+,"1+0"&+#'(,'*(&)$+$(&#'+81+'+8"'
,"#"1,*8",#'*1&'*(&+,(-B
M&)"/"&)"&+'71,$15-"#'1,"'+8$&%#'+8"'"./",$0"&+",'
01&$/4-1+"#B
?:/+8%9$+&')/)&')&2$B%0+%>9)*$+&$!"#
:8(#"'+81+',"-1+"'+('+"*8&(-(%6
2 :6/"#'(='+"*8&(-(%6'(,')"7$*"'E"B%B'?"65(1,)'+6/"F
2 :6/"#'(=')"#$%&'E"B%B')"#$%&'J'7#B')"#$%&'QF
:8(#"'+81+',"-1+"'+('4#",#<'1%"H'%"&)",H'*(0/4+",'
"./",$"&*"H'/,(="##$(&1-')(01$&H'")4*1+$(&H'*4-+4,"H'
0(+$71+$(&H'0(()H'1&)')$#15$-$+$"#
:8(#"'+81+',"-1+"'+('*(&+".+'(='4#"<
2 R86 #$*1-'#+1+4#
2 I#",'#+1+4#
2 S(*$1-'#+1+4#
()/)&')& 2$A%0+%>9)*
!"/"&)"&+'71,$15-"#'E!NF',"=",'+('+8"'(4+*(0"'(,'"=="*+'
+81+'+8"',"#"1,*8",#'1,"'$&+","#+")'$&B'
2 !N'$#')"/"&)"&+'(&'1'/1,+$*$/1&+;#'5"817$(,'(,'+8"'*81&%"#'$&'+8"'MN#
2 !N'$#'4#41--6'+8"'(4+*(0"#'+81+'+8"',"#"1,*8",#'&"")'+('0"1#4,"B
!"/"&)"&+'71,$15-"#'1,"'+8$&%#'+8"'"./",$0"&+",'0"1#4,"#B
?:/+8%9$')/)&')&2$B%0+%>9)*$+&$!"#
T==$*$"&*6<'
2 "B%BH'+1#?'*(0/-"+$(&'+$0"H'#/"")
J**4,1*6<'
2 "B%BH'",,(,',1+"
S45L"*+$7"'#1+$#=1*+$(&<
2 "B%BH'U$?",+ #*1-"',1+$&%#
T1#"'(='-"1,&$&%'1&)',"+"&+$(&',1+"
R86#$*1-'(,'*(%&$+$7"')"01&)
2 "B%BH'KJSJ'+1#?'-(1)'$&)".
C%82 60*
S10"'1#'$&)"/"&)"&+'71,$15- "#B
J&'"./",$0"&+'@$+8'1'*(&+,(-'%,(4/'1&)'1'+,"1+0"&+'%,(4/'$#'1'
#$&%-"V=1*+(,'E(,'(&"V@16F'"./",$0"&+B
T.10/-"<'
2 :@('%,(4/#<'21'#2$';2 %"+#'5,(**(-$'"7",6'0(,&$&%H'<7;217& )("#'&(+B
2 :8"'=1*+(,'(,'$&)"/"&)"&+'71,$15-"'0$%8+'5"'*1--")':778B
2 :8"'0"1#4,"'(,')"/"&)"&+'71,$15-"'$#'&405",'(='/4#84/#'1+'WW'10B'
WX
D)B)9*
U"7"-#'1,"'71-4"#'1'=1*+(,'*1&'1##40"'E$B"B'%,(4/#FB
T.10/-"#<
2 Y1*+(,'=(() 81#'+@('-"7"-#<'5,(**(-$H'&(V5,(**(-$
2 Y1*+(,'?"65(1,) 81#'+@('-"7"-#<'$ZSH'J&),($)
2 Y1*+(,'/(#+4, " 81#'+8,""'-"7"-#<'#$++$&%H'#+1&)$&%H'@1-?$&%
Y$&)$&%')$==","&*"#'10(&%'-"7"-#'$#'@81+'1&'"./",$0"&+'$#'
1--'15(4+B
W[
E)2 < ))&F*;>G)82 *$')*+,&
T1*8'/1,+$*$/1&+'E#45L"*+F'"./",$"& *" #'(&-6'(&"'-"7"-'(='1'
=1*+(,
2 ,"\4$,"#'0(,"'/1,+$*$/1&+#'
2 54+'17($)#'/(##$5-"'*(&=(4&)#
2 "1#$",'+('1&1-6]"'#+1+$#+$*1--6
2 T.10/-"<'
2 R1,+$*$/1&+#'+6/"'4#$&%'"$+8",'$ZS'?"65(1,)'Z^'J&),($)'
?"65(1,)H'54+'&(+'5(+8B'
WD
3+24+&F*;>G)8 2*$')*+,&
T1*8'/1,+$*$/1&+'E#45L"*+F'"./",$"& *" #'1-- -"7"-#'(='1'=1*+(,
2 04*8'0(," '/(@",=4-'#+1+$#+$*1--6
2 54+'*1&'$&+,()4*"'*(&=(4&)#
2 T.10/-"<'
2 R1,+$*$/1&+#'*(0/-"+"'+6/$&%'+1#?#'4#$&%'5(+8'1&'$ZS'
?"65(1,)'JK!'J&),($)'?"65(1,)B'
_8"&'+('4#"'5"+@""&V#45L" *+#'7#B'@$+8$&V#45L"*+#`
Wa
"%00: 6B )0$) 77)82*
:8"'"==" *+'(='(&"'*(&)$+$(&'O*1,,$"#'(7",P'$&+('+8"'&". +'*(&)$+$(&
C(00(&'$&'@$+8$&V#45L"*+')"#$%&#
"B%BH'-"1,&$&%'=,(0'(&"'*(&)$+$(&'+('+8"'&".+
K"4+,1-$]"'*1,,6(7",'"==" *+#'@$+8'counterbalancing
Wb
"6;& 2 )0>%9%&8+&,
C8((#$&%'1&'(,)",'(='/,"#"&+1+$(&'+('&"4+,1-$]"'1&6'
*1,,6(7" ,'"=="*+#B'
:8,""'*(&)$+$(&#<
/W<''JH'QH'C
/X<''JH'CH'Q
/[<''QH'JH'C
/D<''QH'CH'J
/a<''CH'JH'Q
/b<''CH'QH'J
Wc
=4--6'*(4&+" ,51-1& *" )
T.10/-"<'
/W<'$ZSH'J&),($)
/X<'J&),($)H'$ZS
/[<'$ZSH'J&),($)
/D<'J&),($)H'$ZS
d
H+.)'$7%82 60+%9$')*+,&
C(&+1$&#'1+'-"1#+'(&"'5"+@""&V#45L "*+#'=1*+(,'1&)'(&"'@$+8$&V
#45L"*+#'=1*+(,B
J-#('*1--")'#/-$+V/-(+')"#$%&#B
"B%B'!('01-"#'1&)'="01-"#'/",=(,0')$==","&+-6'@$+8')$==","&+'
0(5$-"'?"65(1,)#`
2 Q"+@""&'#45L"*+#'=1*+(,'#". @$+8'+@('-"7"-#<'01-"H'="01-"
2 _$+8$&'#45L"*+#'=1*+(,'?"65(1,) @$+8'+@('-"7"-#<'$ZS 1&)'J&),($)
We
"6&76;&'*
J&6'4&1**(4&+")'=(,'=1*+(,#'+81+'*(4-)'"./-1$&'6(4,',"#4-+#B
S",$(4#'*(&=(4&)#',4$&'"./",$0"&+#B
T.10/-"#<
4&"\41-'+,"1+0"&+#'(,'/,(*")4,"#
2 "B%BH'/1,+$ *$/1&+#'+6/")'a'/8,1#"#'@$+8'$ZS'1&)'Xf'@$+8'J&),($)
#(4,*"#'(='&(&V,1&)(0'71,$1+$(&
2 "B%BH'1--'/1 , +$*$/1&+#'@8('4#")'$ZS'@","'+""&1%"'5(6#
#6#+"01+$*'0"1#4,"0"&+'",,(,
2 "B%BH'+1#?'#+1,+'+$0"'@1#')$==","&+'=(,'J&),($ )'+ 81&'=(,'$ZS
71,$(4#'(+8",'5$1#"#'E)$#*4##")'$&'/,"7$(4#'*-1##"#F
Wg
IB6+'+&,$86&7 6;&'*
^"0(7"'(,'".*-4) "
2 #$0/-6'01?"'+8"'*(&=(4&)'&(+'".$#+
S/,"1)'"\41--6
2 ,1&)(0$]"'#4*8'+81+'+8"'*(&=(4&)'$#'h&($#";
>1&$/4-1+"'1#'1'=1*+(,
2 #6#+"01+$*1--6'*(&+,(-'1'*(&=(4&);# $&=-4"&*"
^"*(,)'1#'1'*(71,$1+"
2 @"'*1&'+8"&'+"#+'@8"+8",'$+'81)'1&'"=="*+
Xf
J%&'61+K% 2+6&
^1&)(0$]1+$(&<'+8"',1&)(0'1##$%&0"&+'(='+,"1+0"&+#'+('
+8"'"./",$0"&+1-'4&$+#'(,'/1,+$*$/1&+#
M&'1'+(+1--6',1&)(0$]")'"./",$0"&+H'&('(&"H'$&*-4)$&%'+8"'
$&7"#+$%1+(,#'+8"0#"-7"#H'$#'15-"'+('/," ) $*+'+8"'*(&)$+$(&'+('
@8$*8'1'/1,+$*$/1&+'$#'%($&%'+('5"'1##$%&")
L0%82+8)=
_8"&'*(0/1,$&%'1'h&"@'+8$&%;'+('1&'h(-)'+8$&%H;'8(@'*1&'@"'
01?"'1'=1$,'*(0/1,$#(&`'
2 @81+'$# 1'= 1$, '*(0/1,$#(&`'E$#'+8","'(&"`F
G(@')('@"'81&)-"'/,1*+$*"`
T.10/-"<
2 :6/$&%'(&'1'=10$-$1,'i_T^:3'?"65(1,)'7",#4#'1'&"@H'
4&=10$-$1,'"./",$0"&+1-'?"65(1,) B
XX
!%&'9+&,$/0%82+8)
^"*,4$+'/1,+$*$/1&+#'@$+8'"\41-'E&(&VF=10$-$1,$+6'@$+8'
+, "1+0"&+#
2 *(4-)'@"'=$&)'/"(/-"'@8('817"'&"7",'4#")'1'i_T^:3'?"65(1,)`
2 @(4-)'+"#+$&%'+8"0'1&#@",'(4,',"#"1,*8'\4"#+$(&`
A$7"'=$.")'10(4&+'(='/,1*+$*"
2 *1&'5"'=$.")'10(4&+'(='+$0"H'(,'=$.")'j '(='+,$1-#
R,1*+$*"'4&+$-'1'*",+1$&'/,(=$*$"&*6'$#'," 1*8")
2 ,"\4$,"#',"1-V+$0"'=" ")51*?H'%('4&+$-'/",=(,01&*"'$#'"\41 -H',"/(,+'
+$0"'+1?"&'+('+81+'/($&+H'+8"&'#+4)6'=4,+8",
^4&'1'-(&%$+4)$&1-'#+4)6
2 +"#+'(7",'04-+$/-"'#"##$(&#'1&)'*(&#+,4*+'-"1,&$&%'*4,7"#
X[
D)%0&+&,$8;0B )*
XD
session or time
proficiency
806**6B)0$/6+&2
Z-)'+"*8&$\4"
K"@'+"*8&$\4"
-.%1/9)$M
GCM',"#"1,*8",#'@1&+")'+(')"+",0$&"'$='+8"'#$]"'(='1')"7$*";#'#*,""&'
1== "*+#'8(@'\4$*?-6'/"(/-"'1,"'15-"'+(',"1)'&"@#'1,+$*-"#B':8"6'
*,"1+")'1&'"./",$0"&+'$&'@8$*8'+8"6'1#?")'Df'/1,+$*$/1&+#'+(',"1)'
1'&"@#'1,+$*-"'(&'"$+8",'1'#01,+@1+*8H'#01,+/8(&"H'+15-"+H'(,'
)"#?+(/B':8"6'0"1#4,")'8(@'-(&%'$+'+((?'"1*8'/1,+$*$/1&+'+(',"1)'
+8"'1,+$*-"B'
Y1*+(,E#F'k'M&)"/"&)"&+'71,$15-"E#F`'
2 _$+8$&'(,'5"+@""&'#45L"*+#`
2 U"7"-#`
!"/"&)"&+'71,$15-"E#F`
R(##$5-"'$##4"#k*(&=(4&)#'+('+8$&?'15(4+`
-.%1/9)$N
M*(&#'$&'4#",'$&+",=1*"#'*1&'5"'4#")'=(,'01&6'/4,/(#"#B'Q4+'1,"'
$*(&#'1-@16#'5"+ +",'+81&'+". +H' (,'1'0$.'(='$*(&#'1&)'+".+H'(,'L4#+'+8"'
+".+`'K$*?$'+,$")'+('1&#@",'+8$#'\4"#+$(&'56'/",=(,0$&%'1'*(&+,(--")'
"./",$0"&+'@$+8'+8,""')$==","&+'$&+",=1*"#'WB'M*(&#'(&-6'XB'M*(&#'@$+8'
*(001&)'&10"'1&)'[B'C(001&)'&10"#'(&-6B':8"'"./",$0"&+'
0"1#4,")'4#",#'/,"=","&*"'=(,'"1*8'(='+8"'+8,""'$&+",=1*"#B
Y1*+(,E#F'k'M&)"/"&)"&+'71,$15-"E#F`'
2 _$+8$&'(,'5"+@""&'#45L"*+#`
2 U"7"-#`
!"/"&)"&+'71,$15-"E#F`
R(##$5-"'$##4"#k*(&=(4&)#'+('+8$&?'15(4+`
-.%1/9)$O
^"#"1,*8",#'@1&+")'+('#+4)6'8(@'+8"'+"0/",1+4,"'(='+8"',((0'
1== "*+")'01-"'1&)'= "01-"'#+4)"&+#'/",=(,01&*"'(&'+8"$,'=$&1-'".10B'
:8"6'#/-$+'+8"'*-1##'$&+('+@('%,(4/#H'@$+8'"1*8'%,( 4/'817$&%'
1//,(.$01+"-6'"\41-'&405",#'(='01-"#'1&)'="01-"#B'Z&"'%,(4/'
*(0/-"+")'+8"'+"#+'$&'1',((0'1+'bf')"%,""#'1&)'+8"'(+8",'1+'gf'
)"%,""#B'^"#"1,*8",#'0"1#4, ")'+8"$,'(7",1--'+"#+'#*(,"'1-(&%'@$+8'
+8"'+$0"'+81+'$+'+((?'+('*(0/-"+"'+8"'+"#+B'
Y1*+(,E#F'k'M&)"/"&)"&+'71,$15-"E#F`'
2 _$+8$&'(,'5"+@""&'#45L"*+#`
2 U"7"-#`
!"/"&)"&+'71,$15-"E#F`
R(##$5-"'$##4"#k*(&=(4&)#'+('+8$&?'15(4+`
T./",$0"&+1-',"#"1,*8',"\4 $,"#'@"--V)"=$&")H'+"#+15-"'
86/ (+8"#"#'+81+'*(&#$#+'(='1'-$0$+")'&405",'(=')"/"&)" &+'
1&)'$&)"/"&)" &+'71,$15-"#B
T./",$0"&+1-',"#"1,*8',"\4 $,"#'#+,$*+'*(&+,(-'(='=1*+(,#'+81+'
016'$&=-4"&*"'+8"')"/"&)"&+'71,$15-"#B'
U15V51#")'"./",$0"&+#'016'&(+'5"'1'%(()',"/,"#"&+1+$(&'
(='4#",#;'+6/$*1-'$&+",1*+$(&'5"817$(,B
T./",$0"&+#')(&"'O$&'+8"'@$-)P'1,"'0(,"')$==$*4-+'+('*(&+,(-B
D+1+2 % 2+6&*$67$-./)0+1) & 2 %9$J)*)%084
I82+B+2:
Work0in0pairs.0
M&'6(4,'/,(L"*+E#FH'@81+'*(&+,(--")'"./",$0"&+'*(4-)'6(4',4&`'
2 _81+'$#'6(4,'86/(+8"#$#`'_81+'$#'+8"'&4--'86/(+8"#$#`
2 _81+'$#'6(4,'O*(&+ ,(-P'%,(4/H'O+,"1+0"&+P'%,(4/E#F`
2 _81+'@(4-)'6(4'817"'/1,+$*$/1 &+#'$&'"1 *8'%,(4/')(`'
2 _81+')1+1'@(4-)'6(4'*(--"*+`
2 B,#2)-9)5731)-;8'%';8';2)0#1-#6&'C9D)E F#<271C9D)#;8)&'0'&9G
2 B,#2)-9)5731)8'%';8';2)0#1-#6&'C9D)E 732<7$'H$'#931'C9DG)
2 B73&8)573)39')#)6'2I'';J936K'<29)71)I-2,-;J936K'<29)8'9-@;G)B,5G
2 _81+'1,"'/(##$5-"'*(&=(4&)#'(,'$##4"#'+('?""/'$&'0$&)`
2 Write0your0name(s)0on0it0and0turn0it0in!