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From |
Amanda Fu <[email protected]> |

To |
[email protected] |

Subject |
Re: st:graph mean with missing groups |

Date |
Sun, 15 Jul 2012 16:11:46 -0400 |

Hello Mr. Nick, Thank you for your response. I understand your suggestion and I knew my question is not clear enough. I find an alternative way to deal with the problem I encountered. Thank you! Amanda On Sun, Jul 15, 2012 at 2:18 PM, Nick Cox <[email protected]> wrote: > This seems puzzling and contradictory to me, which may explain the > lack of replies. > > If groups are empty then the mean of any other variable is undefined > and Stata's refusal to plot the mean is reasonable. It is unknown, or > missing, and not 0. > > On the other hand if what Amanda wants is some kind of histogram or > bar chart, then that can be obtained directly e.g. by -histogram- or > -twoway histogram- and Stata will show empty groups as having zero > frequency, or percent, or density. Such a histogram can be forced to a > line chart by e.g. > > twoway histogram ... , recast(line) > > Nick > > On Sat, Jul 14, 2012 at 1:13 AM, Amanda Fu <[email protected]> wrote: > >> I am stuck with drawing a graph about means of a test score variable >> by groups. The problem is caused by there are some "empty" groups. >> >> The variable "score" range from 0 to 100. I cut it into 10 bands : 0, >> 1-10, 11-20,21-30,...,91-100. I create a new variable "score_percent" >> indicates the percent for the share of observations in each band. >> The data set is like: >> id score score_percent >> 1 32 3.8 (Totally 3.8% observations have scores >> between 31-40) >> 2 89 23.4 >> 3 67 16.5 >> ................... >> I tried to use the following command to create a graph for mean level >> of test scores: >> .twoway connected score_percent score ,xlabel(0(10)100) >> ------------------------- >> However, in the data set none observations have scores from 11-20. So >> this is an empty band. The value of "score_percent" for this band >> should be 0. But if I use the above command to draw the graph, the >> connected line will skip the empty band and directly jump to the next >> point (it is like, along the x-axis there are band 0-10, 21-30,.....). >> What I wanted is to give the empty band with percent share is 0. >> I wonder if someone can give me some suggestion how to fix this. Thank you! >> > * > * For searches and help try: > * http://www.stata.com/help.cgi?search > * http://www.stata.com/support/statalist/faq > * http://www.ats.ucla.edu/stat/stata/ * * For searches and help try: * http://www.stata.com/help.cgi?search * http://www.stata.com/support/statalist/faq * http://www.ats.ucla.edu/stat/stata/

**References**:**st:graph mean with missing groups***From:*Amanda Fu <[email protected]>

**Re: st:graph mean with missing groups***From:*Nick Cox <[email protected]>

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