data loopex4;
seed=11023;
do stickprov=1 to 1000;
    do obs=1 to 80;
    x=100*ranuni(seed);
    output;
    end;
end;
drop obs;
drop seed;
run;

proc summary data=loopex4;
    by stickprov;
    id x;
    output out=WTPmax (drop= _TYPE_ _FREQ_ ) max(x)=;
run;

data WTPmax;
set WTPmax;
    e=(80/((80+1))*100);
    std=SQRT((80*(100*100))/(((80+1)*(80+1))*(80+2)));
    xstd=(x-e)/std;
run;

data WTPmax;
set WTPmax;
    if xstd < -2.5 then xgroup=1;
    if xstd < -1.25 & xstd > -2.5 then xgroup=2;
    if xstd < -0.5 & xstd > -1.25 then xgroup=3;
    if xstd < 0 & xstd > -0.5 then xgroup=4;
    if xstd < 0.5 & xstd > 0 then xgroup=5;
    if xstd > 0.5 then xgroup=6;
run;

proc print data=WTPmax;
run;

proc format;
value groupformat
    1 = '<-2.5'
    2 = '-2.5 - -1.25'
    3 = '-1.25 - -0.5'
    4 = '-0.5 - 0'
    5 = '0 - 0.5'
    6 = '>0.5'
    ;
run;

proc sgplot data=WTPmax;
vbar xgroup / stat=percent barwidth=1 limits=both;
format xgroup groupformat.;
run;