*! version 1.2.5 02jul2007 
program define strs
	version 8
	st_is 2 analysis
	syntax [if] [in] using/ [iw/], BReaks(numlist ascending) Mergeby(namelist) ///
                  [ BY(varlist) DIAGAGE(varname numeric) DIAGYEAR(varname numeric) ATTAGE(name) ATTYEAR(name) ///
                    SURVprob(name) MAXAGE(int 99) STANDstrata(varname numeric) BRENNER ///
                    LIst(namelist) POTfu(varname numeric) Format(string) EDerer1 noTABles /// 
                    SAVE SAVINd(string asis) SAVGRoup(string asis) Level(integer $S_level) * ]

/* Relevant sample */
	marksample touse
	if "`diagage'" == "" {
		cap confirm var age
		local v = _rc
		cap unab okvar : age
		if `v'!=0 | "`okvar'" != "age" {
			display as err "{p}Variable age not found. Your dataset must contain a variable named"
			display as err "age containing age at diagnosis or the name of this variable"
			display as err "specified using the diagage() option.{p_end}"
			exit 198
		}   
		local diagage age
	}
	if "`diagyear'" == "" {
		cap confirm var yydx
		local v = _rc
		cap unab okvar : yydx
		if `v'!=0 | "`okvar'" != "yydx" {
			display as err "{p}Variable yydx not found. Your dataset must contain a variable named"
			display as err "yydx containing calendar year at diagnosis or the name of this variable"
			display as err "specified using the diagyear() option.{p_end}"
			exit 198
		}   
		local diagyear yydx
	}
	markout `touse' `diagage' `diagyear' `by' `standstrata', strok

	if `"`_dta[st_id]'"' == "" {
		di as err /*
		*/ "strs requires that you have previously stset an id() variable"
		exit 198
	}
	cap bysort `_dta[st_id]' : assert _N==1
	if _rc {
		di as err /*
		*/ "strs requires that the data are stset with only one observation per individual"
		exit 198
	}   
	
	confirm file `"`using'.dta"'
	
/* New : weights */
	if "`exp'" != "" {
		cap confirm numeric var `exp'
		if _rc {
			di as err "iweight error: weight variable must be numeric"
			exit 198
		}
		else	unab wei: `exp', max(1) name(iweight uncorrected)
		cap assert `wei' > 0
		if _rc {
			di as err "iweight error: negative weights not allowed"
			exit 198
		}
		cap assert `wei' < 1
		if _rc {
			di as err "iweight error: weights must be less than 1"
			exit 198
		}
		if "`standstrata'" == "" {
			di as err "{p 0 4 2}iweight error: must also specify standstrata(varname) to " 
			di as err "standardize survival estimates when specifying weights.{p_end}" 
			exit 198
		}
	}

/*Check standard strata var and weights */
	if "`standstrata'" != ""{
		if "`exp'" =="" {
			di as err "{p 0 4 2}must also specify weights (using iweight=varname) to standardize"
			di as err "survival estimates across strata of `standstrata'{p_end}"
			exit 198
		}
		cap bysort `by' `standstrata' : assert `wei' == `wei'[_n-1] if _n!=1
		if _rc {
			di as err "iweight error: weights are not constant within each level of `standstrata'"
			exit 198
		}
	}

/* New saving instruction */
	tempfile group_est
	if "`options'"!="" & "`options'"!="save(replace)"{
		local options = subinword("`options'", "save(replace)","",.)
		di as err "option `options' not allowed"
		exit 198
	}
	if "`options'" !=""	local save save
	if "`save'" != "" {
		if "`options'"=="" {
			cap {
				confirm new file individ.dta
				confirm new file grouped.dta
			}
			if _rc {
				di as err "file individ.dta or grouped.dta already exists." _n ///
					  "Use save(replace) to replace these files"
				exit 602
			}
		}
		local indfile individ
		local grfile grouped
		local outrind replace
		local outrgro replace
	}
	// savind(filename[, replace]) 
	if "`savind'" != "" {
		gettoken indfile savind : savind, parse(",")
		gettoken comma savind : savind, parse(",") 
		if `"`comma'"' == "," { 
			gettoken outrind savind : savind, parse(" ,")
			gettoken comma savind : savind, parse(" ,")
			if `"`outrind'"' != "replace" | `"`comma'"'!="" { 
				di as err "option savind() invalid"
			exit 198
			}
		}
		else if `"`comma'"' != "" {
			di as err "option savind() invalid"
			exit 198
		}
		else 	confirm new file `"`indfile'.dta"'
	}
	// savgroup(filename[, replace]) 
	if "`savgroup'" != "" {
		gettoken grfile savgroup : savgroup, parse(",")
		gettoken comma savgroup : savgroup, parse(",") 
		if `"`comma'"' == "," { 
			gettoken outrgro savgroup : savgroup, parse(" ,")
			gettoken comma savgroup : savgroup, parse(" ,")
			if `"`outrgro'"' != "replace" | `"`comma'"'!="" { 
				di as err "option savgroup() invalid"
			exit 198
			}
		}
		else if `"`comma'"' != "" {
			di as err "option savgroup() invalid"
			exit 198
		}
		else 	confirm new file `"`grfile'.dta"'
	}

	if "`format'" == "" local format %6.4f
/* Check that format is valid */
	if "`format'" != "" {
		if index("`format'",",") local format = subinstr("`format'", "," , "." , 1) /* european numeric format */
		local fmt = substr("`format'",index("`format'",".")-1,3) 
		capture {
			assert substr("`format'",1,1)=="%" & substr("`format'",2,1)!="d" ///
				& substr("`format'",2,1)!="t" & index("`format'","s")==0
			confirm number `fmt'
		}
		if _rc {
			di as err "invalid format. format has been set to default %6.4f"
			local format %6.4f
		}
	}

	if "`attage'"=="" {
		cap confirm new var _age
		if _rc {
			display as err "You must specify the variable containing attained age" ///
				" (i.e. age at the time of follow-up)." _n ///
				"This variable cannot exist in the patient data file, but must exist in" ///
    				" the `using' file."
			exit _rc
		}   
		local attage _age
	}
	else {
		capture confirm new variable `attage'
		if _rc {
			display as err "The variable `attage' (specified in the attage option) already exists" ///
       			" in the patient data file." _n ///
      			"This variable cannot exist in the patient data file but must exist in the `using' file."
			exit _rc
		}
	}
	if "`attyear'"=="" {
		cap confirm new var _year
		if _rc {
			display as err "You must specifies the variable containing attained calendar year" ///
				" (i.e. calendar year at the time of follow-up)." _n ///
				"This variable cannot exist in the patient data file, but must exist in" ///
				" the `using' file."
			exit _rc
		}   
		local attyear _year
	}
	else {
		capture confirm new variable `attyear'
		if _rc {
			display as err "The variable `attyear' (specified in the attyear option) already exists" ///
      			" in the patient data file." _n ///
      			"This variable cannot exist in the patient data file but must exist in the `using' file."
			exit _rc
		}
	}
	local inmerby = subinword("`mergeby'","`attage'","",1)
	if "`inmerby'" == "`mergeby'"{			// mergeby does not contain a suitable attained age variable 
		display as err "{p}Variable specifying attained age must be specified in mergeby option."
		display as err "It cannot exist in the patient data file.{p_end}"
			exit 198
	}
	local ininmerby = subinword("`inmerby'","`attyear'","",1)
	if "`ininmerby'" == "`inmerby'"{			// mergeby does not contain a suitable attained year variable 
		display as err "{p}Variable specifying attained year must be specified in mergeby option."
		display as err "It cannot exist in the patient data file.{p_end}"
			exit 198
	}
	if "`ininmerby'" ~= "" {
		foreach name of local ininmerby {
			capture confirm variable `name'
			if _rc	{
      				display as err "mergeby option incorrectly specified." _n ///
        			"`name' must exist in the patient data file."
      				exit _rc
			}
		}
	}
	if "`survprob'"=="" {
		cap confirm new var prob
		if _rc {
			display as err "You must specify a variable in the `using' file which" ///
				" contains the general population survival probabilities." _n ///
				"This variable cannot exist in the patient data file, but must exist in" ///
				" the `using' file."
			exit _rc
		}   
		local survprob prob
	}
	else {
		capture confirm new variable `survprob'
		if _rc {
			display as err "The variable `survprob' (specified in the survprob option) already exists" ///
      			" in the patient data file." _n ///
      			"This variable cannot exist in the patient data file but must exist in the `using' file."
			exit _rc
		}
	}

/* Break list must start from 0 */
 	local i = word("`breaks'",1)
 	if `i' != 0 {
 		display as err "The lifetable intervals in the breaks option must start from 0"
 		exit 198
 	}
*New
/* If there are multiple numlists the interval between them must be at least 1 day */
	tokenize `breaks'    
	while "`2'" != "" {
      		local diff = `2' - `1'
		if `diff' < .00274  local breaks : list breaks - 1
      		mac shift
      	}

	if "`brenner'" != ""{
		if "`standstrata'" == "" {
			di as err "standstrata(varname) must also be specified when using brenner option"
			exit 198
		}
		if "`exp'" == "" {
			di as err "[iweight=varname] must also be specified when using brenner option"
			exit 198
		}
		if "`ederer1'" != "" {
			di as err "Brenner adjustment not allowed for Ederer I method"
			exit 198
		}
		*Check sum of the weights = 1 
		if "`by'"!="" local byby "by `by' : "
		tempvar chkbrw
		qui bysort `by' `standstrata' : g `chkbrw' = `wei' if _n==1
		qui `byby' replace `chkbrw' = sum(`chkbrw')
		cap `byby' assert  `chkbrw'[_N]==1
		if _rc {
			di as err "Using the Brenner adjustment the sum of weigths in the standard population must sum to 1"
			exit 198
		}
	}
	tempvar hakuse
	gen byte `hakuse'=`touse'
	qui replace `touse' = 0 if _st==0
	st_show
	tempvar N
        if `level'<50 | `level'>99 {
		di in red "level() invalid"
		exit 198
	}
	local level = invnorm((1-`level'/100)/2 + `level'/100)

	preserve

	quietly keep if `touse'
/* Brenner weights generated as the ratio between relative proportion of patients in the standard population and in the study population */
	if "`brenner'"!="" {
		if "`by'" != ""	qui bysort `by' : g long `N' = _N 
		else	qui g long `N' = _N 
		qui bysort `by' `standstrata' : replace `wei' = `exp'/(_N/ `N')
		local hakstrata `standstrata'
		local standstrata	
	}
/* By-Standstrata option */
	if "`by'"!="" |	"`standstrata'"!="" local byby "by `by' `standstrata' : "

/* Specify a list of variables to keep */
	keep `_dta[st_id]' `ininmerby' `by' `diagage' `diagyear' _st _d _t _t0 `wei' `standstrata'

/* In the case of late entry pmethod is 2 */
	local pmethod =1
	*qui su _t0, meanonly
	*if `r(min)'!=`r(max)' local pmethod = 2 
	cap assert _t0==0
	if _rc local pmethod = 2 

/* Ederer I method with late entry */
	if "`ederer1'" != "" & `pmethod'==2 {
		di in red "Late entry detected. Ederer I method for expected survival cannot be used."
		exit 184
	}

/* Timescale of potfu must match that of origin */
	if "`potfu'" != "" {
	        cap assert "`_dta[st_orig]'" != "" 
	        if _rc {
	           di as err ///
        	   "To compute Hakulinen estimate strs requires that you have previously stset the origin option. " _n ///
                   " `potfu' must be in the same time scale as `_dta[st_bt]'. See help file for further details."  
                exit 198
        	}   
	}

/* This does the splitting */
	qui {
		stsplit start,at("`breaks'") trim
		keep if _st==1

/**********************************************************************************
Generate attained age and attained year for the new records. These variables must
be integers since we will merge with the popmort file by these variables.  
**********************************************************************************/
		gen `attage'=int(`diagage'+start)
		replace `attage'=`maxage' if `attage'>`maxage'
		gen `attyear'=int(`diagyear'+start)
/* Merge in the external rates */
		sort `mergeby'
		merge `mergeby' using "`using'", nokeep nolabel keep(`survprob')
	}
	
/* Print a warning message if any records do not match with general population file and exit */
	qui count if _merge==1
	if r(N) {
		di in red "`r(N)' records fail to match with general population file " ///
			"(records who do not match are saved to _merge_error_.dta)."
		qui keep if _merge==1
		qui save _merge_error_.dta, replace
		exit 459 
	}
	qui keep if _merge==3 /* Keep only if observations exists in both files */
	drop _merge
	gen y=(_t - _t0) 	/* Person-time at risk in the interval */
	gen d=_d	 	/* Indicator for dead in the interval */

/**********************************************************************************
Expected number of deaths for the interval
Note that survprob is the probability of surviving one year so this will be
correct even for intervals of length other than one year.
**********************************************************************************/
	gen d_star=-ln(`survprob')* y 
	gen nu=(d-d_star)/y 

/**********************************************************************************
stsplit creates a variable with the left cutpoint of each interval
(start) but not the right cutpoint. The right cutpoint will be written
to the variable end.  
**********************************************************************************/
	qui {
		addend, br(`breaks')
		local maxti = r(llist)

/**********************************************************************************
p_star has been calculated as the expected probability of surviving 1 year.
Need to adjust for intervals of lengths other than one.
**********************************************************************************/
		gen p_star=`survprob'^(end-start) 

/* Generate a censoring indicator (not the same as 'not dead') */
		sort `_dta[st_id]' start
		by `_dta[st_id]' : gen w = (d[_N]==0 & _n==_N & y!=(end-start))
		drop `survprob'
	}
*/********************************************************************* 
Save the data set containing the individual subject-band observations.
***********************************************************************/
	label data "Survival data containing individual subject-band observations"
	label variable `diagage' "Age at diagnosis"
	label variable `attage' "Attained age"
	label variable `diagyear' "Diagnosis year"
	label variable `attyear' "Attained year"
	label variable start "Start time of interval"
	label variable end "End time of interval"
	label variable w "Indicator for censored"
	label variable y "Person-time at risk"
	label variable d "Deaths during the interval"
	label variable d_star "Expected number of deaths"
	label variable nu "Estimated excess mortality rate, (d-d_star)/y"
	label variable p_star "Interval-specific expected survival"
	if "`indfile'" != "" qui save "`indfile'", `outrind'

/**********************************************************************************
Collapse the data (i.e. into life table intervals) and calculate survival.
**********************************************************************************/
	if "`brenner'"=="" collapse (sum) d w y d_star (count) n=d (mean) p_star `wei' end, by(`by' `standstrata' start)
	else 	collapse (sum) d w y d_star (count) n=d (mean) p_star [iw=`wei'], by(`by' start end)

	gen n_prime=n-w/2
	gen ns=n_prime-d
	gen nu=(d-d_star)/y 
	local w w
	if `pmethod'==2 {
 		gen p=exp(-(end-start)*d/y)
		local w y
		di as res _n "Late entry detected for at least one observation" ///
		" - p is estimated by transforming the estimated hazard"
	}
	else {
  		gen p=1-d/n_prime
		di as res _n "No late entry detected - p is estimated using the actuarial method" 
	}
	gen r=p/p_star

/* Cumulative observed survival */
/* Updated v1.2.5 (16may2007) to correct bug when p=0 (thanks to John Condon and Arun Pokhrel) */
	qui {
		`byby' gen cp=exp(sum(ln(p))) if p~=0
    replace cp=0 if p==0

/* Cumulative expected survival */
		`byby' gen cp_e2=exp(sum(ln(p_star)))

/* Cumulative relative survival */
		gen cr_e2=cp/cp_e2

/* Standard errors using Greenwood's method */
		gen se_p=sqrt(p*(1-p)/n_prime)
		gen se_r= se_p/p_star 

/* Component of the SE of the cumulative survival */
		`byby' gen se_temp=sum( d/(n_prime*(n_prime-d)) )
		gen se_cp=cp*sqrt(se_temp)
		drop se_temp

/* Calculate confidence intervals on the log-hazard scale and back transform */
/* First for the interval-specific estimates */
 		gen se_lh_p=cond(p!=int(p),sqrt(se_p^2/(p*log(p))^2 ),0)                          
 		gen lo_lh_p=cond(p!=int(p),log(-log(p))+`level'*se_lh_p,0)                        
 		gen hi_lh_p=cond(p!=int(p),log(-log(p))-`level'*se_lh_p,0)                        
		gen lo_p=cond(log(p)!=0,exp(-exp(lo_lh_p)),1,0)                                  
 		gen hi_p=cond(log(p)!=0,exp(-exp(hi_lh_p)),1,0)                                  
		gen lo_r=lo_p/p_star                                         
 		gen hi_r=hi_p/p_star                                         
                                                                                  
/* Calculate CIs for the cumulative estimates */
 		gen se_lh_cp=cond(cp!=int(cp),sqrt(se_cp^2/(cp*log(cp))^2 ),0)     
		gen lo_lh_cp=cond(cp!=int(cp),log(-log(cp))+`level'*se_lh_cp,0)  
 		gen hi_lh_cp=cond(cp!=int(cp),log(-log(cp))-`level'*se_lh_cp,0)   
 		gen lo_cp=cond(log(cp)!=0,exp(-exp(lo_lh_cp)),1,0)
 		gen hi_cp=cond(log(cp)!=0,exp(-exp(hi_lh_cp)),1,0)              
 		gen lo_cr_e2=lo_cp/cp_e2                    
 		gen hi_cr_e2=hi_cp/cp_e2                    
	}

	drop se_lh_p lo_lh_p hi_lh_p se_lh_cp lo_lh_cp hi_lh_cp 

	label variable start "Start of interval"
	label variable end "End of interval"
	label variable n "Alive at start"
	label variable n_prime "Effective number at risk"
	label variable ns "Number of survivors"
	label variable y "Person-time at risk"
	label variable w "Withdrawals during the interval"
	label variable d "Deaths during the interval"
	label variable r "Interval-specific relative survival"
	label variable d_star "Expected number of deaths"
	label variable nu "Estimated excess mortality rate, (d-d_star)/y"
	label variable p_star "Interval-specific expected survival"
	label variable p "Interval-specific observed survival"
	label variable cp "Cumulative observed survival"
	label variable cr_e2 "Cumulative relative survival (Ederer II)"
	label variable cp_e2 "Cumulative expected survival (Ederer II)"
	label variable se_p "Standard error of P"
	label variable se_r "Standard error of R"
	label variable se_cp "Standard error of CP"
	label variable lo_p "Lower 95% CI for P"
	label variable hi_p "Upper 95% CI for P"
	label variable lo_r "Lower 95% CI for R"
	label variable hi_r "Upper 95% CI for R"
	label variable lo_cp "Lower 95% CI for CP"
	label variable hi_cp "Upper 95% CI for CP"
	label variable lo_cr_e2 "Lower 95% CI for CR (Ederer II)"
	label variable hi_cr_e2 "Upper 95% CI for CR (Ederer II)"
	if "`standstrata'"!=""  label var `wei' "Weight"

/********************************************************************* 
Save the data set containing the collapsed data.
***********************************************************************/
	label data "Collapsed (or grouped) survival data"
	format start end %6.0g
	format n d w %6.0f
	format n_prime d_star y %7.1f
	format p p_star r cp cp_e2 cr_e2 se_p se_r se_cp lo_p hi_p lo_r hi_r /// 
		lo_cp hi_cp lo_cr_e2 hi_cr_e2 `format'
	sort `by' `standstrata' start
	local cr  cp_e2 cr_e2 lo_cr_e2 hi_cr_e2  
        local cr2 cp_e2 cr_e2 lo_cr_e2 hi_cr_e2
	local cr_stand cr_e2 lo_cr_e2 hi_cr_e2

	order start end n d d_star ns w n_prime y p se_p lo_p hi_p p_star /// 
		r se_r lo_r hi_r cp se_cp lo_cp hi_cp `cr1' `cr2' `crh' 
	qui save "`group_est'"
	if "`grfile'" != "" qui save "`grfile'", `outrgro'
	
/* Ederer I estimates */
if "`ederer1'" != "" {
         restore,preserve
	 quietly keep if `touse' 
	 qui keep `_dta[st_id]' `ininmerby' `by' `diagage' `diagyear' _st _d _t _t0 `wei' `standstrata'
         qui {
*		 local maxti = word("`breaks'",-1)
                 replace _t = `maxti'
                 stsplit start,at("`breaks'") trim
                 keep if _st==1
                 rename _t end
                 gen `attage'=int(`diagage'+start)
                 replace `attage'=`maxage' if `attage'>`maxage'
                 gen `attyear'=int(`diagyear'+start)
                 sort `mergeby'
                 merge `mergeby' using "`using'", nolabel keep(`survprob')
                 // To fill the surv probabilities where they are unavailable. Note that _m==1 are kept
                 bysort `ininmerby' `attage' (`attyear') : replace `survprob' = `survprob'[_n-1] if `survprob'>=.   
                 drop if _m==2 
                 drop _merge
                 gen p_star=`survprob'^(end-start)
                 bysort `_dta[st_id]' (start) : gen double p_e1 = exp(sum(log(p_star))) 

		/* Brenner approach unallowed */
		collapse cp_e1=p_e1, by(`by' `standstrata' start) 

		sort `by' `standstrata' start
                merge `by' `standstrata' start using "`group_est'"
                drop _m
                gen cr_e1 = cp/cp_e1
		gen lo_cr_e1=lo_cp/cp_e1
                gen hi_cr_e1=hi_cp/cp_e1
                label variable start "Start of interval"
                label variable cp_e1 "Cumulative expected survival (Ederer I)"
                label variable cr_e1 "Cumulative relative survival (Ederer I)"
                label variable lo_cr_e1 "Lower 95% CI for CR (Ederer I)"
                label variable hi_cr_e1 "Upper 95% CI for CR (Ederer I)"
                format cp_e1 cr_e1 lo_cr_e1 hi_cr_e1 `format'
                local cr cp_e1 cr_e1 lo_cr_e1 hi_cr_e1  
                local cr1 cp_e1 cr_e1 lo_cr_e1 hi_cr_e1
		local cr_stand `cr_stand' cr_e1 lo_cr_e1 hi_cr_e1
		sort `by' `standstrata' start
                order start end n d d_star ns w n_prime y p se_p lo_p hi_p p_star /// 
			r se_r lo_r hi_r cp se_cp lo_cp hi_cp `cr1' `cr2' `crh'
		save "`group_est'",replace
                if "`grfile'" != "" save "`grfile'", `outrgro'
         }
}

/* Calculate Hakulinen estimates if potfu() option is specified */
if "`potfu'" != "" {
	restore,preserve
	qui {
		keep if `hakuse'
		if "`brenner'"!="" {
			if "`by'" != ""	qui bysort `by' : g long `N' = _N 
			else	qui g long `N' = _N 
			bysort `by' `hakstrata' : replace `wei' = `exp'/(_N/ `N') 
		}
		if "`_dta[st_ev]'"=="" 	replace `_dta[st_bt]'=`potfu' if `_dta[st_bd]'!=0 & `_dta[st_bd]'<.
		else {
			foreach i of numlist `_dta[st_ev]' {
				replace `_dta[st_bt]'=`potfu' if `_dta[st_bd]'==`i'
			}
		}
		stset
		if `pmethod'==2 {
			tempvar t_ent
			g `t_ent' = _t0
			streset, enter(.)
		}
		keep if _st
		
		/* Specify a list of variables to keep */
		keep `_dta[st_id]' `ininmerby' `by' `diagage' `diagyear' _st _d _t _t0 `wei' `standstrata' `t_ent'

		stsplit start,at("`breaks'") trim
		keep if _st
		addend, br(`breaks')
		gen `attage'=int(`diagage'+start)
		replace `attage'=`maxage' if `attage'>`maxage'
		gen `attyear'=int(`diagyear'+start)
		sort `mergeby'
		merge `mergeby' using "`using'", nokeep nolabel keep(`survprob')
		count if _merge==1
		if r(N) {
			di in red "`r(N)' records fail to match with general population file when estimating" ///
			_n " Hakulinen expected survival (records who do not match are saved" ///
			   " to _mergehak_error_.dta)."
			keep if _m==1
			save _mergehak_error_.dta, replace
			exit 459 
		}
		keep if _merge==3 /* Keep only if observations exists in both files */
		drop _merge
		gen p_star=`survprob'^(end-start)

		bysort `_dta[st_id]' (start) : ///
			gen double l_hak = cond(_n>1,exp(sum(log(p_star[_n-1]))),1)

/* New : Hakulinen estimates if late entry occurs */
		if `pmethod'==2 {
			keep if end > `t_ent'
			bysort `_dta[st_id]' (start) : replace _t0 = `t_ent' if _n==1 
			g double y=(_t - _t0) 	/* Person-time at risk in the interval */
			g d = l_hak*(1-sqrt(p_star)) * (y!=(end-start)) + l_hak*(1-p_star) * (y==(end-start))
/* If lost */		bysort `_dta[st_id]' (start) : replace d = l_hak*(1-p_star^.25) ///
					if (end-`t_ent')!=(_t-`t_ent') & _n==1 & `t_ent'>0 
			gen w_hak = l_hak * sqrt(p_star) * (y!=(end-start))
/* If lost */		bysort `_dta[st_id]' (start) : replace w_hak = l_hak*p_star^.25*1.5 ///
					if (end-`t_ent')!=(_t-`t_ent') & _n==1 & `t_ent'>0 
			if "`brenner'"=="" collapse (sum) l_hak w_hak d, by(`by' `standstrata' start)
			else  collapse (sum) l_hak w_hak d [iw=`wei'], by(`by' start)
			gen g = 1 - d / (l_hak - 0.5*w_hak)
			drop d l_hak w_hak
		}
		
		else {
			gen y=(_t - _t0) 	/* Person-time at risk in the interval */
			gen w_hak = l_hak*sqrt(p_star) * (y!=(end-start))
			gen delta = l_hak*(1-sqrt(p_star)) * (y!=(end-start)) 
			gen l_plus = l_hak * p_star* (y==(end-start))
			if "`brenner'"=="" collapse (sum) l_hak l_plus w_hak delta, by(`by' `standstrata' start)
			else  collapse (sum) l_hak l_plus w_hak delta [iw=`wei'], by(`by' start)
			gen f = w_hak+delta
			gen g=0.25*(l_hak-0.5*f)^(-2)* ///
				(-0.5*delta+sqrt(0.25*delta^2+4*(l_hak-0.5*f)* ///
					(l_plus+0.5*w_hak)))^2
			drop l_hak l_plus w_hak delta f
		}

		`byby' gen cp_hak = exp(sum(ln(g)))
		sort `by' `standstrata' start
		merge `by' `standstrata' start using "`group_est'"
		keep if _m==3
		drop _m
		gen cr_hak = cp/cp_hak
		gen lo_cr_h=lo_cp/cp_hak                    
		gen hi_cr_h=hi_cp/cp_hak
		label variable g "Interval expected survival (Hakulinen)"
		label variable cp_hak "Cumulative expected survival (Hakulinen)"
		label variable cr_hak "Cumulative relative survival (Hakulinen)"
		label variable lo_cr_h "Lower 95% CI for CR (Hakulinen)"
		label variable hi_cr_h "Upper 95% CI for CR (Hakulinen)"
		label variable start "Start of interval"
		label variable end "End of interval"
		format cp_hak cr_hak lo_cr_h hi_cr_h g `format'
		format start end %6.0g
		local cr cp_hak cr_hak lo_cr_h hi_cr_h 
		local crh cp_hak cr_hak lo_cr_h hi_cr_h 
		local cr_stand `cr_stand' cr_hak lo_cr_h hi_cr_h
		order start end n d d_star ns w n_prime y p se_p lo_p hi_p p_star /// 
			r se_r lo_r hi_r cp se_cp lo_cp hi_cp `cr1' `cr2' `crh'
		if "`grfile'" != "" save "`grfile'", `outrgro'
	}	
}

/* Show tables */
if "`tables'" == "" {
	sort `by' `standstrata' start
	if "`brenner'"!="" {
		di as res _n "Adjusted survival estimates weighting individual observations as proposed" ///
			" by Brenner."
	}
	if "`list'"=="" `byby' list start end n d `w' p p_star r cp `cr', table noobs
	else {
		foreach name of local list {
			cap confirm var `name'
			if _rc    di as err "WARNING: `name' invalid or ambiguous in list option" 
			else	  unab ilist: `name'
			local tolist "`tolist' `ilist'"
		}
		local st_end "start end"
		if "`by'" != "" local tolist : list tolist - by
		local tolist : list tolist - st_end
		`byby' list start end `tolist', table noobs
	}
			
/* Weighted average of survival estimate */
	if "`standstrata'"!="" {
*Erase intervals where some standstrata are missing
		qui inspect `standstrata'
		qui bysort `by' start: drop if _N!=`r(N_unique)'
*Check if in some standstrata cumulative relative survival exceeds 1 or estimates in previous intervals
		cap assert p<=p_star
		local chr = _rc
*Check if weighted CIs are appropriate
		collapse `cr_stand' [iw=`wei'], by(`by' start end)
		di as res _n "Adjusted survival estimates weighting stratum-specific survival in each group" ///
			" of `standstrata' by `exp' weights."
		if "`by'"!=""	local byby : list byby - standstrata
		else local byby 
		`byby' list start end cr_e2 lo_cr_e2 hi_cr_e2 `cr_stand', table noobs
		if `chr'>0 { 
			di in smcl as txt "{p}Note that in some group of `standstrata' cumulative relative survival exceeds 1 or " ///
			"the estimate in any previous interval.{p_end}"
		}
	}
}
end

program define addend, rclass
	version 8.0
	syntax, BReaks(numlist ascending)
	tokenize `breaks'
	gen end=.
*New
while "`2'" != "" {
      		replace end=`2' if round(float(start),0.0001)==round(float(`1'),0.0001)
      		mac shift
      	}
	ret scalar llist = `1'
end