Comparing three continuous measures over time. What is the command

[Don Spady]

I apologize for my ignorance, but I have not done any statistical analysis for several years and am very rusty in my use of Stata 12. I have a dataset containing a unique id for each record and three continuous measures for each id. The measures were taken sequentially at different times. There are no missing data. Thus the variables are: id, base, t1, t2. What is the command in Stata 12 to compare the values of base vs t1 and t1 vs t2 and base vs t2.
Many thanks for answering this

[Carlo Lazzaro]

Don:
if you want to compare:
1) base vs t1;
2) base vs t2;
3) t1 vs t2,
I would perform three -ttest- with alfa=.05/3.

[Don Spady]

Cario. Thanks for the advice. I thought about it a bit more and figured out what to do.

Reshape long, then oneway and options does the job.

[Carlo Lazzaro]

Don:
another approach that springs to my mind is:

. use "C:\Program Files\Stata17\ado\base\a\auto.dta"
(1978 automobile data)

. mvreg headroom trunk turn = i.foreign

Equation             Obs   Parms        RMSE    "R-sq"          F      P>F
--------------------------------------------------------------------------
headroom              74       2    .8142408    0.0863   6.804771   0.0110
trunk                 74       2     4.01917    0.1292   10.68196   0.0017
turn                  74       2    3.436215    0.3983   47.65754   0.0000

------------------------------------------------------------------------------
             | Coefficient  Std. err.      t    P>|t|     [95% conf. interval]
-------------+----------------------------------------------------------------
headroom     |
     foreign |
    Foreign  |  -.5402098   .2070884    -2.61   0.011    -.9530329   -.1273867
       _cons |   3.153846   .1129149    27.93   0.000     2.928754    3.378938
-------------+----------------------------------------------------------------
trunk        |
     foreign |
    Foreign  |  -3.340909   1.022208    -3.27   0.002    -5.378643   -1.303175
       _cons |      14.75   .5573585    26.46   0.000     13.63893    15.86107
-------------+----------------------------------------------------------------
turn         |
     foreign |
    Foreign  |  -6.033217    .873943    -6.90   0.000     -7.77539   -4.291043
       _cons |   41.44231   .4765172    86.97   0.000     40.49239    42.39223
------------------------------------------------------------------------------

. test [headroom]

 ( 1)  [headroom]0b.foreign = 0
 ( 2)  [headroom]1.foreign = 0
       Constraint 1 dropped

       F(  1,    72) =    6.80
            Prob > F =    0.0110

.