Type mismatch even for same type variables?!

[Amarylis Durand]

Hi,

I'm using Stata/SE 12.0 with Windows 10 and I've been blocking for a while on something. The only post I found on the subject was from Paula de Souza but what was suggested there does not seem to work in my case.

I have merged 2 files and what I want is that when the variable gdp_o has missing values, it would be replaced by GDP values but I keep getting the "type mismatch" error. GDP was a string14, I have done destring but then GDP becomes a "double, %10.0g" type while gdp_o is a "float, %9.0g" type. So when I want to replace, I get:

Result # of obs.
-----------------------------------------
not matched 21,638
from master 20,750 (_merge==1)
from using 888 (_merge==2)

matched 587,218 (_merge==3)
-----------------------------------------

. order Countryrep Coderep Codepar year GDP gdp_o gdp_d

. replace GDP ="." if GDP ==".." | GDP =="_"
(18449 real changes made)

. destring GDP, replace ignore(" ")
GDP has all characters numeric; replaced as double
(39200 missing values generated)

.
. format gdp_o %10.0g

. format gdp_d %10.0g

. replace gdp_o =GDP if gdp_o == "."
type mismatch
r(109);

Then I tried
compress GDP

compress GDP
. format gdp_o %10.0g

. recast float GDP
GDP: 565006 values would be changed; not changed

. recast float GDP
GDP: 565006 values would be changed; not changed

. recast double gdp_o gdp_d /// to convert gdp_o in double

. recast double gdp_o gdp_d
. format gdp_o gdp_d %10.0g

> format gdp_o gdp_d %10.0g*/
. recast float GDP, force
GDP: 564053 values changed
. replace gdp_o =GDP if gdp_o == "."
type mismatch




It would be great if someone could tell me why I keep having this mismatch message, even when I see in the variables manager table that the 2 variables are the same type.
Thanks a lot!

[Jorrit Gosens]

The type mismatch is not because var A mismatched with var B, it is because you are using string manipulation on a numeric var or vice versa. See below example

. list

     +--------------+
     | var1    var2 |
     |--------------|
  1. |    1     one |
  2. |    .      .  |
  3. |    3   three |
     +----

. gen missvar1 = 1 if var1=="."
type mismatch
r(109);
. gen missvar1 = 1 if var1==.
(2 missing values generated)


. gen missvar2 = 1 if var2==.
type mismatch
r(109);
. gen missvar2 = 1 if var2=="."
(2 missing values generated)

[Nick Cox]

Jorrit pointed out your mistake. Specifically, gdp_o is numeric. So its values can't be strings. Indeed.you yourself gave it a numeric display format and recast it to double. Neither would have been possible if it were a string variable.

[Amarylis Durand]

Hi Jorrit and Nick,

It works, thank you so much!

Here it is:

replace GDP ="." if GDP ==".." | GDP =="_"
destring GDP, replace ignore( )
replace gdp_o =GDP if gdp_o == .