fix bug in estimation input: first_obs

src/+gui_auxiliary/set_command_option.m

@@ -73,7 +73,7 @@ try
             end
 
         case 'first_obs'
-            options_.first_obs = value;
+            options_.first_obs = str2num(value);
 
         case 'use_bandpass_filter'
             options_.bandpass.indicator = value;