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Re: st: Calculating trendline in stata


From   Tinofa Mutevedzi <tinofamutevedzi@gmail.com>
To   statalist@hsphsun2.harvard.edu
Subject   Re: st: Calculating trendline in stata
Date   Wed, 23 Apr 2014 23:30:51 +0200

Dear Richard,

what I want is I have panel data by year covering all years between
2003-2013, and in each year, I calculate mean age at first sex. I then
graph these means which reveal a pattern of the age at first sex over
time, separately for females and males. I now want to assess if the
trend pattern I am observing is statistically different. For variables
that are proportions like proportion using condoms, I use ptrend
command in stata. But I don't know what to do if its a mean?

regards,

Tinofa Mutevedzi

On 23 April 2014 14:19, Richard Goldstein <richgold@ix.netcom.com> wrote:
> your question remains unclear; e.g., why not just use -regress-?
>
> Rich
>
> On 4/22/14, 5:29 PM, Tinofa Mutevedzi wrote:
>> Dear Richard,
>>
>> thank you. But your explanation only works for proportions. What if I
>> want a trendline for means?
>>
>> On 7 March 2014 16:54, Richard Goldstein <richgold@ix.netcom.com> wrote:
>>> it is not at all clear what your question is; this is a very simple, and
>>> limited, command taking 3 arguments and no options: the first argument
>>> is a variable with the number of positives (e.g., events) and the second
>>> is the number of negatives (so their sum is the total number of tries)
>>> and third is the x variable for the regression
>>>
>>> if this setup does not match your data then you probably want a
>>> different command (e.g., -logistic- or -glogit- or -blogit-)
>>>
>>> Rich
>>>
>>> On 3/7/14, 9:42 AM, Tinofa Mutevedzi wrote:
>>>>
>>>> Could someone please help me with the command for ptrend from a module
>>>> by Patrick Royston.
>>>>
>>>> regards,
>>>>
>>>> Tinofa Mutevedzi
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