whatsnew7to8.hlp

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{smcl}
{* 03may2005}{...}
{cmd:help whatsnew7to8}
{hline}

{title:What's new in release 8.0 (compared to release 7)}

{pstd}
This file lists the changes corresponding to the creation of Stata
release 8.0:

    {c TLC}{hline 67}{c TRC}
    {c |} help file       contents                   dates                  {c |}
    {c LT}{hline 67}{c RT}
    {c |} {help whatsnew}        Stata 9.0                  22apr2005 to present   {c |}
    {c |} {help whatsnew8to9}    Stata 9.0 new release      22apr2005              {c |}
    {c |} {help whatsnew8_2}     Stata 8.2                  28oct2003 to 24feb2005 {c |}
    {c |} {help whatsnew8_1}     Stata 8.1                  01jul2003 to 30sep2003 {c |}
    {c |} {help whatsnew8_0}     Stata 8.0                  14jan2003 to 25jun2003 {c |}
    {c |} {bf:this file}       Stata 8.0 new release      02jan2003              {c |}
    {c |} {help whatsnew7}       Stata 7.0                  08jan2001 to 05dec2002 {c |}
    {c |} {help whatsnew6to7}    Stata 7.0 new release      15dec2000              {c |}
    {c |} {help whatsnew6}       Stata 6.0                  13jan1999 to 20nov2000 {c |}
    {c BLC}{hline 67}{c BRC}

{pstd}
Most recent changes are listed first.


{hline 3} {hi:more recent updates} {hline}

{pstd}
See {help whatsnew8_0}.


{hline 3} {hi:Stata 8.0 release 02jan2003} {hline}

{p 4 4 2}
As always, Stata 8.0 is 100% compatible with the previous release of Stata,
but as always we remind programmers that it is vitally important that you put
{cmd:version 7.0} at the top of your old do-files and ado-files if they are
to work; see help {help version}. You were supposed to do that when you wrote
them but, if you did not, go back and do it now. We have made a lot of changes
(improvements) to Stata.

{p 4 4 2}
In addition, Stata's dataset format has changed because of the new longer data
storage types and the fact that Stata now has multiple representations for
missing values. You will not care because Stata automatically reads old-format
datasets, but if you need to send a dataset to someone still using Stata 7,
remember to use the {cmd:saveold} command; see help {help saveold}.

{p 4 4 2}
The features added to Stata 8.0 are listed under the following headings.

	    {bf:What's big}
		{bf:Graphics}
		{bf:GUI}
	    {bf:What's useful}
	    {bf:What's convenient}
	    {bf:What was needed}
	    {bf:What's faster}
	    {bf:What's new in time-series analysis}
	    {bf:What's new in cross-sectional time-series analysis}
	    {bf:What's new in survival analysis}
	    {bf:What's new in survey analysis}
	    {bf:What's new in cluster analysis}
	    {bf:What's new in statistics useful in all fields}
	    {bf:What's new in data management}
	    {bf:What's new in expressions and functions}
	    {bf:What's new in display formats}
	    {bf:What's new in programming}
	    {bf:What's new in the user interface}
	    {bf:What's more}


{title:What's big}

{p 4 4 2}
The big news is the new GUI and the new Graphics.  There is no putting them in
an order.


    {title:Graphics}

{p 4 4 2}
You can create graphs that look like this

{p 12 12 2}
({stata gr_example2 line3:click to run})

{p 4 4 2}
or this

{p 12 12 2}
({stata "gr_example auto: twoway (qfitci mpg weight, stdf) (scatter mpg weight), by(foreign)":click to run})

{p 4 4 2}
See {hi:A quick tour} in help {help graph_intro}.  Everything you need to know
is online.

{p 4 4 2}
So what's new in Stata graphics?  Everything.  There is not one little bit
that is not new, even if it seems familiar.

{p 4 4 2}
Before you panic, let us tell you that all the old graphics are still
in Stata.  If you type

	{cmd:. graph7} ...

{p 4 4 2}
or

	{cmd:. gr7} ...

{p 4 4 2}
you will be back to using the old {cmd:graph} command; see help {help graph7}.
Moreover, the old {cmd:graph} command is still invoked under version control;
see help {help version}.  If you set your version to 7.0 or earlier,
{cmd:graph} does not mean what is defined in help {help graph}; it means what
it used to mean, which means that old do-files and ado-files continue to work.

{p 4 4 2}
One new feature requires some adjustment.  What used to be called symbols are
now called markers, and marker symbols are the shapes of the markers.  Thus,
you no longer specify the {cmd:symbol()} or {cmd:s()} option, you specify the
{cmd:msymbol()} or {cmd:ms()} option.  In addition, the old {cmd:s(.)} for
specifying the dot symbol is now {cmd:ms(p)} ({cmd:p} stands for point).
{cmd:ms(.)} means to use the default.

{p 4 4 2}
All existing statistical commands that produce graphs have been updated
to take advance of the new graphics.


    {title:GUI}

{p 4 4 2}
GUI stands for Graphical User Interface, and to try it, you do not need to
read a thing.  Pull down {hi:Data}, {hi:Graphics}, or {hi:Statistics}, find
what you are looking for, and click.

{p 4 4 2}
Fill in the dialog box and click to submit.  Do not ignore tabs at the top --
there are very useful things hidden under them.

{p 4 4 2}
If you know the command you want, you can skip the menus and type {cmd:db}
followed by the command name.  For instance you can jump directly to the
{cmd:stcox} dialog box by typing {cmd:db stcox} (or
{dialog stcox:click here}).  See help {help db}.


{title:What's useful}

{p 4 4 2}
Stata 8 has so many features that finding what you are looking for can be a
challenge.  We have addressed that:

{p 6 10 2}
1.  Pull down {hi:Help} and select {hi:Contents}.  You will be presented with
    the categories Basics, Data management, Statistics, Graphics, and
    Programming.  Click on one of them -- say, Statistics -- and you will be
    presented with another set of categories:  Summary statistics and tests,
    Tables, Estimation, Multivariate analysis, Resampling and simulation,
    Statistical hand calculations, and Special topics.  Click on one of those
    and, well, you get the idea.  With the new {cmd:help contents}, it never
    takes long to find what you need.

{p 6 10 2}
2.  Help files now have hyperlinks in the header for launching the dialog
    associated with the command.  So, there are three ways to launch a dialog
    box:  (1) use the menus (pull down {hi:Data}, {hi:Graphics}, or
    {hi:Statistics}); (2) use the new {cmd:db} command (see help {help db});
    or (3) pick the command from the online help.

{p 6 10 2}
3.  When you do need to search, {cmd:findit} is the key.  {cmd:findit}
    searches everywhere:  Stata itself, the Stata web site, the FAQs, the
    {it:Stata Journal}, and even user-written programs available on the web.
    An earlier version of {cmd:findit} was made available as an update to
    Stata 7, but the new version is better.  You can also access {cmd:findit}
    by pulling down {hi:Help} and selecting {hi:Search}.  If you do that, be
    sure to click {hi:Search all} in the dialog box.  See help {help search}.

{p 6 10 2}
4.  The new {cmd:ssc} command lists and installs user-written packages from
    the Statistical Software Components (SSC) archive, also known as the
    Boston College Archive, located at {browse "http://www.repec.org"}.  See
    help {help ssc}.

{p 6 10 2}
5.  The new {cmd:net sj} command makes loading files from the new
    {it:Stata Journal} easier; see help {help net}.


{title:What's convenient}

{p 4 4 2}
The existing {cmd:set} command has a new {cmd:permanently} option that allows
you to make the setting permanent.  This does away with the necessity of
having a {cmd:profile.do} file for most users.


{title:What was needed}

{p 4 4 2}
Stata now has multiple missing values!  In addition to the previously existing
{cmd:.}, there is now {cmd:.a}, {cmd:.b}, ..., {cmd:.z}, and you can attach
value labels to the new missing codes!

{p 4 4 2}
One thing to watch out for:  Do not type

{p 8 12 2}
	{cmd:.} {it:stata_command} ... {cmd:if} {it:x} {cmd:!= .}

{p 4 4 2}
Instead, type

{p 8 12 2}
	{cmd:.} {it:stata_command} ... {cmd:if} {it:x} {cmd:< .}

{p 4 4 2}
You need remember this only if you use the new missing values, but better to
have good habits.  The way things now work,

{p 8 12 2}
	{it:all numbers} < {cmd:.} < {cmd:.a} < {cmd:.b} < ... < {cmd:.z}

{p 4 4 2}
So, if you wanted to list all observations for which {it:x} is missing, you
would type

{p 8 12 2}
	{cmd:. list if} {it:x} {cmd:>= .}

{p 4 4 2}
See help {help missing}.


{title:What's faster}

{p 4 4 2}
Stata 8 executes programming commands in half the time of Stata 7, on average.
This results in commands implemented as ado-files running about 17 to 43%
faster.

{p 6 10 2}
1.  This speed-up is due to a new, faster memory manager that reduces the
    time needed to find, access, and store results.  Thus, the improvement
    does not change much the time to run built-in, heavily computational
    commands.  {help regress}, for instance, runs only 1.43% faster.
    Nevertheless, the effect can be marked on other commands.  {help poisson}
    runs up to 31% faster, and {help heckman} runs up to 43% faster.  The
    larger the dataset, the less will be the improvement:  {cmd:heckman} runs
    17% faster on 4,000 observations.

{p 6 10 2}
2.  That statistical commands run faster is a happy side effect.  The big
    advantage of the speed-up is that it allows some problems to be approached
    using ado-files that previously would have required internal code, such as
    Stata's new graphics, which is an ado-file implementation!  Some
    programming commands run up to 400% faster.  Implementing features as
    ado-files is part of the effort to keep Stata open and extendable by
    users.


{title:What's new in time-series analysis}

{p 6 10 2}
1.  Stata now can fit vector autoregression (VAR) and structural vector
    autoregression (SVAR) models.  New commands {cmd:var}, {cmd:varbasic}, and
    {cmd:svar} perform the estimation; see help {help varintro}.

{p 10 14 2}
    a.  A suite of {cmd:varirf} commands estimate, tabulate, and graph
	impulse-response functions, cumulative impulse-response functions,
	orthogonalized impulse-response functions, structural impulse-response
	functions, and their confidence intervals, along with forecast-error
	variance decompositions and structural forecast-error variance
	decompositions; see help {help varirf}.  This suite allows graphical
	comparisons of IRFs and variance decompositions across models and
	orderings.

{p 10 14 2}
    b.  {cmd:varfcast} produces dynamic forecasts from a previously fitted
	{cmd:var} or {cmd:svar} model; see help {help varfcast}.

{p 10 14 2}
    c.  There is also a full suite of diagnostic and testing tools including

{p 16 20 2}
	i.  {cmd:vargranger}, that performs Granger causality tests; see help
	    {help vargranger}.

{p 15 20 2}
	ii.  {cmd:varlmar}, that performs a Lagrangian multiplier (LM)
	     test for residual autocorrelation; see help {help varlmar}.

{p 14 20 2}
	iii.  {cmd:varnorm}, that performs a series of tests for normality of
	      the disturbances; see help {help varnorm}.

{p 15 20 2}
	iv.  {cmd:varsoc}, that reports a series of lag order selection
	     statistics; see help {help varsoc}.

{p 16 20 2}
	v.  {cmd:varstable}, that checks the eigenvalue stability condition;
	    see help {help varstable}.

{p 15 20 2}
	vi.  {cmd:varwle}, that performs a Wald test that all the endogenous
	     variables of a given lag are zero, both for each equation
	     separately and for all equations jointly; see help {help varwle}.

{p 6 10 2}
2.  The new {cmd:tssmooth} command smooths and predicts univariate time series
    using weighted or unweighted moving average, single exponential smoothing,
    double exponential smoothing, Holt-Winters nonseasonal smoothing,
    Holt-Winters seasonal smoothing, or nonlinear smoothing.  See help
    {help tssmooth}.

{p 6 10 2}
3.  The new {cmd:tsappend} command appends observations to a time-series
    dataset, automatically filling in the time variable and the panel
    variable, if set, by using the information contained in {cmd:tsset}.  See
    help {help tsappend}.

{p 6 10 2}
4.  The new {cmd:archlm} command computes a Lagrange multiplier test for
    autoregressive conditional heteroskedasticity (ARCH) effects in the
    residuals after {help regress}; see help {help archlm}.

{p 6 10 2}
5.  The new {cmd:bgodfrey} command computes the Breusch-Godfrey Lagrange
    multiplier (LM) test for serial correlation in the disturbances after
    {help regress}; see help {help bgodfrey}.

{p 6 10 2}
6.  The new {cmd:durbina} command computes the Durbin (1970) alternative
    statistic to test for serial correlation in the disturbances after
    {help regress} when some of the regressors are not strictly exogenous; see
    help {help durbina}.

{p 6 10 2}
7.  The new {cmd:dfgls} command performs the modified Dickey-Fuller t test for
    a unit root (proposed by Elliott, Rothenberg, and Stock (1996)) using
    models with 1 to {it:maxlags} lags of the first differenced variable in an
    augmented Dickey-Fuller regression; see help {help dfgls}.