whatsnew8_1.hlp

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    confidence intervals in the binomial case is unchanged.  See help
    {help ci} for details.

{p 5 9 2}
{* enhancement}
2.  {help codebook} now allows {cmd:if} {it:exp} and {cmd:in} {it:range}
    qualifiers; see help {help codebook}.

{p 5 9 2}
{* fix}
3.  {help findfile}, when used with the {cmd:all} option, saved results in the
    return list with unbalanced double quotes; this is fixed.

{p 5 9 2}
{* fix}
4.  {help graph} has improved axis titles when time-series operators are
    applied to a variable that does not have a label.  Previously the title
    did not include the variable name, only the time-series operator(s).  The
    title now includes {it:ts}{cmd:.}{it:varname} where {it:ts} are the
    time-series operator(s) and {it:varname} is the variable name.

{p 5 9 2}
{* enhancement}
5.  {help graph_bar:graph bar} has new options {cmd:over(, reverse)} and
    {cmd:yvaroptions(reverse)} that specifies the categorical scale be
    reversed to run from maximum to minimum rather than the default minimum
    to maximum.  See help {help graph_bar}.

{p 5 9 2}
{* fix}
6.  Several of the {help by_option:graph by()} suboptions could "stick",
    meaning that they would be applied to subsequent graphs drawn with the
    {cmd:by()} option even though the options were not specified
    subsequently.
    Suboptions that could "stick" were {cmd:xtitles}, {cmd:ytitles},
    {cmd:edgelabel}, {cmd:individual}, {cmd:ixaxes}, {cmd:iyaxes},
    {cmd:ixtitles}, {cmd:iytitles}, {cmd:ixticks}, {cmd:iyticks},
    {cmd:rescale}, {cmd:xrescale}, and {cmd:yrescale}.  This has been fixed.

{p 5 9 2}
{* fix}
7.  {help twoway_mband:graph twoway mband} for plots with only two
    observations now connects the two points in the data.  Previously no line
    was drawn.

{p 5 9 2}
{* enhancement}
8.  {help twoway_mband:graph twoway mband} and
    {help twoway_mspline:graph twoway mspline} now have better default number
    of bands.

{p 5 9 2}
{* fix}
9.  {help twoway_mspline:graph twoway mspline} for plots with only two unique
    values of the {it:x} variable now plots the two unique points and the
    medians for the {it:y} variables at those two points.  Previously a
    clearly incorrect line was drawn.

{p 4 9 2}
{* enhancement}
10.  {help hausman} has new option {cmd:df()} for controlling the degrees of
     freedom for the Hausman test; see help {help hausman}.

{p 4 9 2}
{* fix}
11.  {help hausman} could incorrectly state which model was consistent and
     which inconsistent-but-efficient in the message presented at the bottom
     of the output table; this is fixed.

{p 4 9 2}
{* fix}
12.  {help ml} when used with an {cmd:if} or {cmd:in} restriction, could
     produce the error "{it:tempvar} not found" in rare instances;
     this is fixed.

{p 4 9 2}
{* fix}
13.  When the {help maximize:nrtolerance()} option of maximum-likelihood
     estimators (such as {cmd:heckman}) or {help ml:ml maximize} was
     specified, the tolerance could be declared met even if the Hessian was
     not positive definite.  Now the Hessian must be positive definite as a
     precondition for the {cmd:nrtolerance()} convergence criterion.

{p 4 9 2}
{* fix}
14.  {help palette:palette linepalette} now honors the {cmd:scheme()} option.

{p 4 9 2}
{* fix}
15.  {help recode}, in the case of rule overlap, used the last matching rule,
     rather than the first matching rule as documented; this is fixed.
     In addition, {cmd:recode} is now faster.

{p 4 9 2}
{* enhancement}
16.  {help schemes:Scheme files} may now have {cmd:*!} comments.  This allows
     their version to be displayed by {help which}.

{p 4 9 2}
{* enhancement}
17.  {help svymarkout} is a new programmer's command for marking observations
     for exclusion based on survey characteristics set by {help svyset};
     see help {help svymarkout}.

{p 4 9 2}
{* fix}
18.  {help twoway__function_gen} could produce values of "x" greater than
     indicated in the {cmd:range()} option; this is fixed.


{hline 8} {hi:update 01jul2003} {hline}

    {title:What's new in release 8.1 (compared to release 8.0)}

{p 5 9 2}
{* enhancement}
1.  {help ml} has lots of new features; see help {help ml} and see the book
    {it:{browse "http://www.stata.com/bookstore/mle.html":Maximum Likelihood Estimation with Stata, 2d Edition}}
    (Gould, Pitblado, and
    Sribney 2003).

{p 9 13 2}
    a.  {cmd:ml} can now perform BHHH, DFP, and BFGS optimization techniques
	with user defined likelihood functions.  The default technique
	remains modified Newton-Raphson.

{p 9 13 2}
    b.  {cmd:ml} has a new variance estimator -- outer product of the
	gradients (OPG) -- to accompany the two previously available --
	the Hessian-based estimator and the robust estimator.  The new
	{cmd:vce()} option along with the existing {cmd:robust} option
	specify which is used:

{p 13 13 2}
	{cmd:vce(hessian)} specifies the Hessian-based variance estimator.

{p 13 13 2}
	{cmd:vce(opg)} specifies the outer-product-of-the-gradients variance
	estimator.

{p 13 13 2}
	{cmd:robust} specifies the Huber/White robust estimator.

{p 9 13 2}
    c.  {cmd:ml} handles irrelevant constraints, if specified, more elegantly.
        Previously, irrelevant constraints caused an error message.  Now they
        are flagged and ignored.

{p 13 13 2}
	{cmd:ml model} uses the new command {help makecns} when
	supplied with the {cmd:constraint()} option.  {cmd:makecns} uses
	{help matconst:matrix makeCns} to generate a constraint matrix, and
	displays a note for each constraint that causes a problem; see help
	{help makecns}.

{p 13 13 2}
	(Prior to version 8.1, {cmd:ml} would ignore the {cmd:constraint()}
	option if there were no predictors in the first equation.  This
	behavior is preserved under version control.  Under {cmd:version 8.1},
	{cmd:ml} applies constraints under all circumstances.)

{p 9 13 2}
    d.  Constraints now imply a Wald test for the model chi-squared test.  For
	those who wish to perform likelihood-ratio tests for models with
	constraints, see help {help lrtest}.

{p 9 13 2}
    e.  {help mlmatbysum} is a new programmer's command for use by method
	{cmd:d2} likelihood evaluators to help define the negative Hessian
	matrix in the case of panel-data likelihoods; see help
	{help mlmatbysum}.

{p 5 9 2}
{* enhancement}
2.  Plugins (also known as DLLs or shared objects) written in C can now be
    incorporated into and called from Stata.  Point your browser to
    {browse "http://www.stata.com/support/plugins/"}
    for more information and documentation.

{p 5 9 2}
{* enhancement}
3.  {help sts:sts graph} has new options {cmd:cihazard} and
    {cmd:per(}{it:#}{cmd:)}.  {cmd:cihazard} draws pointwise confidence bands
    around the smoothed hazard function.  {cmd:per()} specifies the units used
    to report the survival or failure rate.  See help {help sts} for details.

{p 5 9 2}
{* enhancement}
4.  (Windows, Macintosh, and Linux) {help odbc} has new commands
    {cmd:odbc insert} and {cmd:odbc exec} for writing data to an ODBC data
    source.  Positioned updates are also possible using the {cmd:odbc exec}
    command.  See help {help odbc} for more information.

{p 5 9 2}
{* enhancement}
5.  The constant and current-value class {cmd:c()} has the following new items.

		{cmd:c(alpha)}      (lowercase letters)
		{cmd:c(ALPHA)}      (uppercase letters)
		{cmd:c(Mons)}       "Jan Feb ... Dec"
		{cmd:c(Months)}     "January February March ... December"

{p 9 9 2}
    See help {help creturn}.

{p 5 9 2}
{* enhancement}
6.  {help outfile} has new option {cmd:missing} that preserves all missing
    values when the {cmd:comma} option is also specified.  Previously, if you
    specified {cmd:comma}, system missing values ({cmd:.}) were changed to
    null strings ({cmd:""}) and extended missing values ({cmd:.a}, {cmd:.b},
    ..., {cmd:.z}) were retained.  See help {help outfile}.

{p 5 9 2}
{* enhancement}
7.  {help _svy_mkdeff}, {help _svy_mkmeff}, {help _get_eformopts}, and
    {help _get_diparmopts} are new programmer utilities.

{p 5 9 2}
8.  Recommendation on setting version at the top of do-files and ado-files:
    Use {cmd:version 8.1}.  {cmd:version 8.1} adds new features and
    changes the behavior of {help ml} for the better.
    (Setting {cmd:version 8.0} restores {cmd:ml}'s old behavior.)
    See help {help version}.


    {title:Other additions and fixes}

    {title:Ado-files}

{p 5 9 2}
{* enhancement}
9.  {help nlogit} now uses the {help maximize:BFGS} optimization algorithm by
    default.

{p 4 9 2}
{* fix}
10.  {help nlogit} ignored the {cmd:robust} option when the specified model
     had more than 3 levels.  The {cmd:robust} option is no longer allowed
     when the specified model has more than 3 levels.

{p 4 9 2}
{* fix}
11.  {help zip} and {help zinb} with the {cmd:vuong} option now report an
     error if constraints are also specified.


    {title:Stata executable}

{p 4 9 2}
{* fix}
12.  {help insheet} did not honor the {cmd:double} option; this is fixed.

{p 4 9 2}
{* fix}
13.  (Windows) {help insheet} incorrectly identified very large integer values
     as fitting within type {help long} instead of {help double}; this is
     fixed.

{p 4 9 2}
{* enhancement}
14.  {help _pctile} will now compute up to 1000 percentiles (previously the
     limit was 20); see help {help _pctile}.  In addition, {help pctile}
     (no underscore) takes
     advantage of {cmd:_pctile}'s new higher limit, and is more precise in
     determining the boundaries between the requested percentiles.

{p 4 9 2}
{* enhancement}
15.  (Macintosh) The {hi:Browse...} dialog from the Viewer has been changed to
     allow selection of either files or folders.

{p 4 9 2}
{* fix}
16.  (Macintosh) {help update:update swap} has been altered to resolve a
     problem some users were having in updating to a new executable.

{p 4 9 2}
{* fix}
17.  (Macintosh) Clicking the toolbar switch button in the
     {help doedit:Do-file editor} to show the toolbar when it was previously
     hidden would not properly refresh the area between the text and the
     toolbar; this is fixed.


{hline 8} {hi:previous updates} {hline}

{pstd}
See {help whatsnew8_0}.

{hline}


{title:Also see}

{psee}
Online:  {help whatsnew}
{p_end}