. * nwrem tutorial 3: comparing specifications and limits
. * Requires the core nwcommands and the package nwrem.
. * Run from this folder; the data are in ../data.
. 
. * --- declare the events (see tutorial 1) ---
. import delimited "../data/calls_events.csv", clear
(encoding automatically selected: ISO-8859-1)
(3 vars, 439 obs)

. levelsof sender, local(a) clean
1 2 5 7 8 11 16 20 21 23 24 27 29 30 31 32 36 37 42 43 44 46 47 51 55 58 62 64 66 67 68 70 71 72

. levelsof receiver, local(b) clean
1 3 4 6 8 9 11 12 14 16 20 21 22 23 24 25 27 30 31 32 33 34 35 36 42 43 44 45 46 50 51 54 55 58 60 61 63 64 66 67 68 70 
> 71 74 76 77

. local all : list a | b

. local miss

. forvalues i = 1/84 {
  2.     if !`: list i in all' local miss `miss',`i'
  3. }

. local miss = substr("`miss'", 2, .)

. nwset sender receiver, directed eventtime(eventtime) name(calls)

. nwaddnodes calls, nodenames(`miss')

. 
. * --- five specifications ---
. quietly nwrem calls, nodsnd nidrec

. estimates store m1

. quietly nwrem calls, frpsndsnd frrecsnd

. estimates store m2

. quietly nwrem calls, nodsnd nidrec frpsndsnd frrecsnd

. estimates store m3

. quietly nwrem calls, rsndsnd rrecsnd

. estimates store m4

. quietly nwrem calls, nodsnd nidrec rsndsnd rrecsnd

. estimates store m5

. 
. * --- compare: log likelihood, number of parameters, AIC and BIC ---
. estimates stats m1 m2 m3 m4 m5

Akaike's information criterion and Bayesian information criterion

-----------------------------------------------------------------------------
       Model |          N   ll(null)  ll(model)      df        AIC        BIC
-------------+---------------------------------------------------------------
          m1 |        439          .  -3117.419       2   6238.837   6247.006
          m2 |        439          .  -2274.048       2   4552.096   4560.265
          m3 |        439          .   -2115.76       4   4239.519   4255.857
          m4 |        439          .  -2122.016       2   4248.032   4256.201
          m5 |        439          .  -1968.845       4   3945.689   3962.027
-----------------------------------------------------------------------------
Note: BIC uses N = number of observations. See [R] IC note.

. lrtest m3 m1

Likelihood-ratio test
Assumption: m1 nested within m3

 LR chi2(2) = 2003.32
Prob > chi2 =  0.0000

. lrtest m3 m2

Likelihood-ratio test
Assumption: m2 nested within m3

 LR chi2(2) = 316.58
Prob > chi2 = 0.0000

. 
. * --- do the estimates depend on the optimiser's starting point? ---
. nwrem calls, nodsnd nidrec frpsndsnd frrecsnd seed(1)
-----------------------------------------------------------------------------
Relational event model (ordinal partial likelihood, MLE)
Network: calls                         Actors: 84
Events: 439                            Log likelihood: -2.12e+03
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
       calls | Coefficient  Std. err.      z    P>|z|     [95% conf. interval]
-------------+----------------------------------------------------------------
      nodsnd |   5.392444    .437614    12.32   0.000     4.534736    6.250151
      nidrec |   .9485508   .5809881     1.63   0.103     -.190165    2.087267
   frpsndsnd |   5.782833   .1612639    35.86   0.000     5.466762    6.098905
    frrecsnd |   1.640031   .1538416    10.66   0.000     1.338507    1.941555
-----------------------------------------------------------------------------

. nwrem calls, nodsnd nidrec frpsndsnd frrecsnd seed(2)
-----------------------------------------------------------------------------
Relational event model (ordinal partial likelihood, MLE)
Network: calls                         Actors: 84
Events: 439                            Log likelihood: -2.12e+03
-----------------------------------------------------------------------------
-----------------------------------------------------------------------------
       calls | Coefficient  Std. err.      z    P>|z|     [95% conf. interval]
-------------+----------------------------------------------------------------
      nodsnd |   5.392423   .4376143    12.32   0.000     4.534715    6.250131
      nidrec |   .9485645   .5809885     1.63   0.103    -.1901521    2.087281
   frpsndsnd |    5.78284   .1612634    35.86   0.000      5.46677    6.098911
    frrecsnd |   1.640016   .1538413    10.66   0.000     1.338493     1.94154
-----------------------------------------------------------------------------

. 
. * --- what is refused ---
. capture noisily nwrem calls
nwrem requires at least one effect: nodsnd nidrec nidsnd nodrec ntdegsnd ntdegrec frpsndsnd frrecsnd covsnd() covrec() c
> ovint() covevent() rsndsnd rrecsnd (see nwrem for what each computes; the development notes for what is not yet implem
> ented).
invalid syntax

. display "return code: " _rc
return code: 198

. capture noisily nwrem calls, frpsndsnd covsnd(nosuchvar)
variable nosuchvar not found
(error in option covsnd())

. display "return code: " _rc
return code: 111

. 
. * --- a network that is not an event network ---
. nwrandom 8, prob(.3) name(ordinary)

. capture noisily nwrem ordinary, nodsnd
nwrem requires a network declared via nwset's eventtime() option (an event-type temporal network) - see nwset.
invalid syntax

. display "return code: " _rc
return code: 198

.