From monthly to yearly in %

[Samantha Will]

Hello!

* Example generated by -dataex-. For more info, type help dataex
clear
input float(fundnr month year mf_m_cf)
1  7 2011          .
1  8 2011   81.92355
1  9 2011   476.8079
1 10 2011   21.52062
1 11 2011   2.582487
1 12 2011   6.664676
1  1 2012   8.380138
1  2 2012   1.357534
1  3 2012   8.550103
1  4 2012  -2.678535
1  5 2012   5.655555
1  6 2012   2.504373
1  7 2012 -.12116786
1  8 2012  4.5901546
1  9 2012    .600794
1 10 2012  .29563415
1 11 2012   3.328934
1 12 2012  1.4961462
1  1 2013  .54998076
1  2 2013   4.551462
1  3 2013   .6748788
1  4 2013   .4444814
1  5 2013 -.01265101
1  6 2013   .6499855
1  7 2013  1.6610664
1  8 2013   2.949057
1  9 2013   3.399674
1 10 2013   9.943465
1 11 2013   .2990036
1 12 2013  -.3797645
1  1 2014  -1.064931
1  2 2014  .24728173
1  3 2014   1.374272
1  4 2014  -3.390731
1  5 2014    .359465
1  6 2014  -.4076815
1  7 2014 -1.1045641
1  8 2014   -.697988
1  9 2014  -.8082402
1 10 2014 -.13452792
1 11 2014  1.3073466
1 12 2014 -2.0818634
1  1 2015  -4.356202
1  2 2015  2.8146536
1  3 2015  -.6765027
1  4 2015  -83.74078
2  8 2011          .
2  9 2011  4.5467353
2 10 2011   6.979911
2 11 2011  8.1631975
2 12 2011   .6553888
2  1 2012  1.0961826
2  2 2012  -2.891215
2  3 2012  1.5067998
2  4 2012   24.91592
2  5 2012  -.2980085
2  6 2012  -.4910712
2  7 2012 -.22777045
2  8 2012  -.9225484
2  9 2012  -.8890392
2 10 2012 -1.3467927
2 11 2012  -3.202692
2 12 2012 -2.0998995
2  1 2013   5.050189
2  2 2013   3.924864
2  3 2013  -1.263452
2  4 2013  -.5413366
2  5 2013  1.5253117
2  6 2013  -.9724789
2  7 2013 -3.5416684
2  8 2013  -.2780949
2  9 2013  -.4938647
2 10 2013   4.586828
2 11 2013  .23677163
2 12 2013  -1.385884
2  1 2014  .13616227
2  2 2014  -2.955069
2  3 2014 -1.5510585
2  4 2014 -1.4003643
2  5 2014  .27552602
2  6 2014  -.7300715
2  7 2014  -.8981757
2  8 2014 -1.3882908
2  9 2014 -1.1608492
2 10 2014   1.369086
2 11 2014   .7596431
2 12 2014 -4.2625575
2  1 2015  1.0341657
2  2 2015  -.0750414
2  3 2015 -.20450144
2  4 2015  -2.822578
2  5 2015  -.9178555
2  6 2015 -1.2965387
2  7 2015  -.3353655
2  8 2015   2.649211
2  9 2015 -.32353655
2 10 2015  -.0687631
2 11 2015  -.9628157
2 12 2015 -1.1600745
2  1 2016  -.8803672
end

For clarification: mf_m_cf stands for 'Monthly Flow in % following Sirri/Tufano' and I am trying to get the yearly flow in %. I dont think I can just add the monthly flow in % for each fundnr in each year, is there perhaps a Stata function for this?

[Ken Chui]

Would be better to get the actual flow per month and then compute the change again after summing them up to annual. Summing percentage is tricky because the denominator will change. +20% and -20% would add up to 0 but in reality: 100 * 1.2 = 120, and then 120 * .8 would be 96, not 100.