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Update, November 1998 (from STB-46)

**Note:** the updates are
cumulative. (STB-46) denotes files that have been changed since the
previous update.

- (STB-46)
**svymlog**,**svyolog**,**svyoprob**

The options**deff**,**deft**,**meff**,**meft**,**prob**, and**ci**did not work when specified at runtime (they did, however, work on redisplay). They now work. - (STB-45)
**canon**

The reported model chi-squared was (slightly) incorrect; it is now**canon**previously issued an error message when either equation contained only one variable. - (STB-45)
**reshape**

**reshape long**would confuse variables with names like v8 and v80 when v8 was mentioned but not exist. - (STB-45)
**svytab**

New command**svytab**produces two-way tabulations with tests for independence. It is for use with complex survey data or other clustered data. - (STB-45)
**xttab**

**xttab**did not calculate the within-percentage correctly in unbalanced data. - (STB-44)
**heckman**

The reported model chi-squared was (slightly) incorrect; it is now calculated correctly. - (STB-44)
**reshape**

**reshape**would produce the odd message "___ values would be changed" and then proceed to give correct results. The message is now suppressed. - (STB-44)
**sts**

Specifying**graph, twoway**'s**ylog**option with**sts graph**produced an error. - (STB-44)
**table**

Standard deviations are now reported correctly when aweights are specified. - (STB-44)
**xtgls**

**xtgls**, when computing AR(1) correlations by panel for a large number of panels, did not place all the correlations in the saved result S_E_rho. There were no errors in reported results. - (STB-44)
**xtreg**

**xtreg, fe**now uses better logic for dropping of constant-within-panel variables. Previously, a constant variable might not be dropped and then results looked odd (but were correct). - (STB-43)
**heckman**

**heckman**now has the capability to estimate models with variables that perfectly predict selection. Previously**heckman**would simply drop such variables from the selection equation, which is inappropriate in most cases. - (STB-43)
**kap**

**kap**has been modified to deal with a large number ratings. Previously, it would issue the error message "too many ratings". - (STB-43)
**kdensity**

**kdensity**now works correctly with**aweights**. - (STB-43)
**stack**

**describe**, run after**stack**, no longer shows that the data is saved under a temporary filename. - (STB-43)
**sts**

The new**atrisk**for use with**sts graph**shows the number of subjects at risk at the beginning of each interval; see help**sts**. - stata52. (STB-42)
**sts**

**sts graph**now plots survival curves, etc., from time t=0 rather than from the first observed time of failure or censoring. The new**noorigin**option restores the original behavior. - (STB-42)
**bstrap**,**bsample**

These commands did not work with the**idcluster()**option; they now do. - (STB-42)
**kap**

One of the new syntax features introduced for**kap**in STB-41 — the ability to specify more than two variables — did not work; doing that returned a syntax error. All new features work now. - (STB-41)
**fracpoly**,**fracplot**,**fracgen**

**fracplot**now produces a component+residual plot for Cox regression using martingale residuals. Previously, no residuals were used. (You can recover the old type of plot by using the undocumented**nopts**option.) In addition, the following changes to the output have been made:

- P-values from F-tests presented when option
**compare**is specified have been corrected: previously they did not correctly account for the degrees of freedom associated with estimation of the FP powers. The change is very slight in most cases. - The
**compare**table has been reformatted slightly: a column for df has been added and the column previously labelled P is now labelled P(term). -
**fracgen**reports creation of new variable(s) followed by the phrase "if _sample", stressing the use of an estimation sample.

- P-values from F-tests presented when option
- (STB-41)
**lincom**

The new**hr**option allows the output to be labeled as Hazard Ratios, which is useful when**lincom**is used after survival estimators. - stata51 (STB-41)
**mcc**,**mcci**

**mcc**and**mcci**now report the exact McNemar test in addition to what was previously reported. There is no change in command syntax. (Programmers: the new significance value is stored in the global macro**$S_24**.) - (STB-41)
**ologitp**,**oprobitp**

These commands now work after the**svyolog**and**svyoprob**commands introduced in STB-40. - (STB-41)
**reshape**

**reshape**now handles blanks in filenames correctly. - (STB-41)
**svyolog**,**svyoprob**,**svymlog**

Previously these commands — introduced in STB-40 — did not handle zero weights properly; now they do. - (STB-41)
**weibull**

**weibull**now converges more rapidly. - stata49 (STB-40)
**kap**

A new**absolute**option is added for dealing with unobserved outcomes and a syntax addition allows**kap**to be used as an alternative to**kappa**. - stata50 (STB-40)
**ttest**,**ttesti**,**sdtest**,**sdtesti**

**ttest**and**ttesti**now display standard deviations. In addition, string variables are allowed with**by()**.**sdtest**and**sdtesti**previously reported incorrect one-sided p-values — the degrees of freedom where interchanged — the two-sided p-value was corrrect. This is fixed. In addition,**sdtest**and**sdtesti**now display standard deviations and string variables are allowed with**by()**. - svy6 (STB-40)
**svymlog**,**svyolog**,**svyoprob**

Three new commands, equivalent to**mlogit**,**ologit**, and**oprobit**, are introduced for estimating multinomial logistic and ordered logit and probit models using complex survey data. - (STB-40)
**boxcox**

In rare cases,**boxcox**issued an error message when option**mean**was specified. - (STB-40)
**cttost**

**cttost**issued the error message "invalid syntax" instead of "option invalid" when an invalid option was specified. - (STB-40)
**ir**

**ir**ignored irrelevant options rather than issuing the error "option invalid". - (STB-40)
**stack**

The new**group()**option provides an easier way to use**stack**. In addition,**stack**'s**into()**option now understands variable ranges. - (STB-40)
**stereg**,**ereg**

If**score(**was specified and the model was estimated in the log-time metric,*newvar*)**stereg**and**ereg**created newvar with the sign reversed. This is fixed. - (STB-40)
**sureg**

Previously degrees of freedom were calculated as N-round(mean(k1,k2,...))*e, where N is the number of observations, k1, the number of estimated parameters less the intercept in the first equation, k2 the same thing for the second equation, etc., and e the number of equations. This has been changed to N-round(mean(k1,k2,...)). - (Stata website)
**xtgee**,**xtpois**,**xtprobit**

Estimation of the exchangeable working correlation parameter was incorrect in the presence of singletons — groups containing single observations. In the presence of singletons, the estimated working correlation was attenuated; if the proportion of singletons was small, the effect was negligible. (This same bug affected S-plus and SAS's PROC GENMOD.)In addition, these commands are updated to change the calculation of the scale parameter. Formerly, N was used as the divisor; now N-k is used. Either will work in that any consistent estimate of phi is adequate, but most other implementations use N-k.

There are two parts to this update: the updated xtgee.ado ado-file and an updated executable. Your Stata executable needs to be dated at least 14 Oct 1997 (type

**query born**to the Stata prompt). If it is older than that, obtain the latest executable. - (STB-39)
**bs**

Very long (over 600 character)**bs**commands could result in an "invalid syntax" error. The problem is now fixed. - (STB-39)
**kap**

**kap**now displays tables with missing rows/columns more prettily. - (STB-39)
**reshape**

All new syntax is introduced; the new**reshape**command continues to understand the old syntax. - (STB-39)
**sw**

**sw**now may be used with**nbreg**. - (STB-38)
**stbase**

**stbase**without the**at()**option produced incorrect results when either the data had gaps or there were multiple failures per subject. In such cases,**stbase**lost the observation on the first failure of each subject.**stbase**produced correct results when the data did not have gaps and there were no multiple failures per subject. - (STB-38)
**ttest**,**ttesti**

**ttest**and**ttesti**now produce answers when one of the groups has only one observation. - (STB-37)
**areg**

**areg**refused to produce estimates of the constant-only model when no regressors were specified. - (STB-37)
**sts**

The**t2title()**option did not work;**sts graph**ignored it. - (STB-37)
**svyratio**

**svyratio**with the**by()**option did not label the output clearly. - (STB-37)
**xtgee**

The**noconstant**option did not work;**xtgee**refused to estimate the model. - (STB-36)
**bs**

Previously,**bs**was supposed to have a**cluster()**option but did not. It now does. - (STB-36)
**cs**

**cs**with the**by()**option produced incorrect Mantel-Haenzel combined risk ratio when one or more of the strata had infinite risk ratios (no cases in the strata). To produce the incorrect result, (1) you had to specify the**by()**option, (2) you must not have specified the**or**or**rd**options (which would cause**cs**to report something other othan risk ratios), and (3) there must have been one or more strata with infinite risk ratios (risk ratio reported as missing in the output). The incorrectly calculated result is now fixed. - (STB-36)
**dotplot**

Previously, the**mean****median**and**nogroup**options did not work: if you specified them, you got a syntax error. They now work. In addition, new options**vert****bounded**and**incr()**have been added. - (STB-36)
**lincom**

**lincom**now allows longer expressions. - (STB-36)
**merge**

There was no problem. The on-line help file, however, incorrectly said that the**nokeep**option omitted observations that would have been marked**_merge==1**when it should have said that it omitted observations that would have been marked**_merge==2** - (STB-36)
**matrix**

There was no problem. The on-line help file, however, provided an incorrect syntax diagram for**matrix accum** - (STB-36)
**prtest****prtesti**

These commands now report the standard error under the null hypothesis in addition to the statistics previously reported. - (STB-36)
**sts**

**sts graph**with the**adjustfor()**option could produce titles for graphs that were so long that Stata would then refuse to draw the graph. - (STB-36)
**sw**

**sw**may now be used with**clogit** - (STB-36)
**ttest****ttesti**

**ttest**and**ttesti**now include a**level()**option to specify the level for the confidence interval. - (STB-36)
**xtgee**

The criteria for detecting divergence of the model was updated. - (STB-35)
**bitest**,**bitesti**

For certain extreme values of the test statistic,**bitest**and**bitesti**would report a two-sided p-value of 1 rather than 0. - crc46 (STB-35)
**dydx**,**integ**

These commands have been improved and now fit a cubic spline to the data and use that to produce the derivative and integral. - (STB-35)
**joinby**

Under rare circumstances**joinby**would produce a dataset with no observations when it should have produced something else. Note that if the old**joinby**produced a dataset that had any observations, it was correct. - (STB-35)
**loneway**

When there were weights and missing values of the outcome or group variables,**loneway**did not produce the correct ANOVA table. This is fixed. In addition, you are warned that there may still be outstanding issues with this command concerning the reliability statistic and the intraclass correlation coefficient; see Gleason (1997), sg65: Computing intraclass correlations and large ANOVAs, STB-35. - (STB-35)
**stir**

The note at the top that reports which values corresponded to the exposed and unexposed categories was backwards. Statistics were correct. - crc45 (STB-35)
**stset**

Two new options have been added to**stset****first**and**force****first**specifies that events after the first failure event in time-varying data are to be ignored.**force**drops obsrvations with missing values of the time, outcome,**id()****t0()**or weighting variables. See help**stset**. - (STB-35)
**sw**

**sw**leaves behind variable**_sample**for use by other programs. This variable indicates which observations were used in producing results.**_sample**was incorrectly not set to 0 for observations containing missing values of the dependent variable even though such observations were not used. Note that the stepwise results reported were correct.

In addition, two more changes were made:**sw regress**now allows the**beta**option.**sw logistic**now allows the**robust**and**cluster()**options. - (STB-35)
**xtgee**,**xtprobit**,**xtpois**

Three changes are made. First, the divergence criterion for probit and logit models is relaxed, making the "estimates diverging" error message less likely. Second, the**noconstant**option may now be spelled out as the manaul indicates. Before the change, it had to be abbreviated. Third, the time variable**t()**is now required in the case of**corr(fixed)** -
**bsample, bstrap, bs**

Due to an error in**bsample**, the**cluster()**option on all three of these commands did not give a proper bootstrap sample. -
**egen ... pctile()**

**egen**'s**pctile()**function now allows noninteger percentiles. Previously, only integer percentiles were allowed; noninteger percentiles resulted in an error message. - (STB-34)
**mvdecode**

**mvdecode**has been improved to handle float variables containing decimal-encoded missing values. -
**mvreg**

Degrees of freedom were reported incorrectly. - (STB-34)
**prtest, sdtest, ttest**

These commands produced obviously incorrect output when the grouping These commands produced obviously incorrect output when the grouping variable was labeled and the label contained blanks.

In addition, confidence intervals were labeled 95% even when other than 95% was requested (the requested confidence interval was, however, shown). -
**sts graph**

**sts graph**with the**lost**option produced incorrect Kaplan-Meier plots (without the**lost**option results were correct).

In addition,**sts graph**has been modified to display the Kaplan-Meier curve out to the last censoring or death. Previously, the curve was displayed out to the last death only. - (STB-34)
**sw**

**sw**refused to allow**pweight**s or**iweight**s. - (STB-34)
**xtgee, xtprobit**

When faced with certain inestimable models,**xtgee**and**xtprobit**would report "conformability error". The error message is improved. In addition, the checks for diverging models were improved.In addition,

**sts graph**has been modified to display the Kaplan-Meier curve out to the last censoring or death. Previously, the curve was displayed out to the last death only.