twoway_mband.hlp

是一个经济学管理应用软件 很难找的 但是经济学学生又必须用到

{smcl}
{* 08apr2005}{...}
{cmd:help mband}{right:dialogs:  {dialog twoway_overlay:overlaid twoway}{space 0}}
	{right:{dialog twoway_simple:single twoway}{space 2}}
{hline}

{p2colset 5 31 33 2}{...}
{p2col :{hi:[G] graph twoway mband} {hline 2}}Twoway median-band plots{p_end}
{p2colreset}{...}


{title:Syntax}

{p 8 54 2}
{cmdab:tw:oway}
{cmd:mband}
{it:yvar}
{it:xvar}
{ifin}
[{cmd:,}
{it:options}]

{p2colset 9 31 33 2}{...}
	{it:options}{col 31}description
{p2line}
	{cmdab:b:ands:(}{it:#}{cmd:)}{...}
{col 31}number of bands

INCLUDE help gr_clopt

INCLUDE help gr_axlnk

INCLUDE help gr_twopt
{p2line}
{pin}
All options are {it:rightmost}; see {help repeated options}.


{title:Description}

{pstd}
{cmd:twoway} {cmd:mband} calculates
cross medians and then graphs the cross medians as a line plot.


{title:Options}

{phang}
{cmd:bands(}{it:#}{cmd:)}
    specifies the number of bands on which the calculation is to be based.
    The default is max(10, round(10*log10(N))), where N is the number of
    observations.

{pmore}
    In a median-band plot, the {it:x} axis is divided into {it:#}
    equal-width intervals and then the median of {it:y} and the
    median of {it:x} are calculated in each interval.
    It is these cross medians that {cmd:mband} graphs as a line plot.

{phang}
{it:cline_options}
     specify how the median-band line is rendered and its appearance;
     see {it:{help cline_options}}.

INCLUDE help gr_axlnkf

INCLUDE help gr_twoptf


{title:Remarks}

{pstd}
Remarks are presented under the headings

	{help twoway mband##remarks1:Typical use}
	{help twoway mband##remarks2:Use with by()}


{marker remarks1}{...}
{title:Typical use}

{pstd}
Median bands provide a convenient but crude way to show the tendency in the
relationship between {it:y} and {it:x}:

	{cmd:. sysuse auto, clear}

	{cmd:. scatter mpg weight, msize(*.5) || mband mpg weight}
	  {it:({stata "gr_example auto: scatter mpg weight, msize(*.5) || mband mpg weight":click to run})}
{* graph gtmband1}{...}

{pstd}
The important part of the above is "{cmd:mband} {cmd:mpg} {cmd:weight}".
On the {cmd:scatter}, we specified {cmd:msize(*.5)} to make the marker
symbols half their normal size; see {it:{help relativesize}}.


{marker remarks2}{...}
{title:Use with by()}

{pstd}
{cmd:mband} may be used with {cmd:by()} (as can all the {cmd:twoway} plot
commands):

	{cmd:. scatter mpg weight, ms(oh) ||}
	{cmd:  mband mpg weight ||, by(foreign, total row(1))}
	  {it:({stata "gr_example auto: scatter mpg weight, ms(oh) || mband mpg weight ||, by(foreign, total row(1))":click to run})}
{* graph gtmband2}{...}

{pstd}
In the above graph, we specified {cmd:ms(oh)} so as to use hollow symbols;
see {it:{help symbolstyle}}.


{title:Also see}

{psee}
Manual:  {bf:[G] graph twoway mband}

{psee}
Online:  
{helpb line},
{helpb twoway mspline},
{helpb twoway lfit},
{helpb twoway qfit},
{helpb twoway fpfit}
{p_end}