Code:
* Example generated by -dataex-. To install: ssc install dataex
clear
input float(date amzn ibm)
18627    180 146.76
18630 184.22 147.48
18631 185.01 147.64
18632 187.42 147.05
18633 185.86 148.66
18634 185.49 147.93
18637 184.68 147.64
18638 184.34 147.28
18639 184.08  149.1
18640 185.53 148.82
end
format %td date
Code:
. list date amzn ibm in 1/10

     +-----------------------------+
     |      date     amzn      ibm |
     |-----------------------------|
  1. | 31dec2010      180   146.76 |
  2. | 03jan2011   184.22   147.48 |
  3. | 04jan2011   185.01   147.64 |
  4. | 05jan2011   187.42   147.05 |
  5. | 06jan2011   185.86   148.66 |
     |-----------------------------|
  6. | 07jan2011   185.49   147.93 |
  7. | 10jan2011   184.68   147.64 |
  8. | 11jan2011   184.34   147.28 |
  9. | 12jan2011   184.08    149.1 |
 10. | 13jan2011   185.53   148.82 |
     +-----------------------------+
I would like to generate two variables amzidx and ibmidx: amzidx will be amzn divided by 1st obs of amzn (180) and ibmidx will be ibm divided by 1st obs of ibm (146.76). It should look like the following.
Code:
. list in 1/10

     +---------------------------------------------------+
     |      date     amzn      ibm    amznidx     ibmidx |
     |---------------------------------------------------|
  1. | 31dec2010      180   146.76          1          1 |
  2. | 03jan2011   184.22   147.48   1.023444   1.004906 |
  3. | 04jan2011   185.01   147.64   1.027833   1.005996 |
  4. | 05jan2011   187.42   147.05   1.041222   1.001976 |
  5. | 06jan2011   185.86   148.66   1.032556   1.012946 |
     |---------------------------------------------------|
  6. | 07jan2011   185.49   147.93     1.0305   1.007972 |
  7. | 10jan2011   184.68   147.64      1.026   1.005996 |
  8. | 11jan2011   184.34   147.28   1.024111   1.003543 |
  9. | 12jan2011   184.08    149.1   1.022667   1.015944 |
 10. | 13jan2011   185.53   148.82   1.030722   1.014037 |
     +---------------------------------------------------+