Remove panel IDs under a specific condition

[Christos Tzomakas]

Hello,

I am having trouble removing PANELIDs that do not fulfill a specific condition. I want to delete all the PANELIDs in which they have at least one observation (quarter) where the ret variable is greater than or equal to 0.

input float(time PANELID ret)
156 1           .
157 1           .
158 1           .
159 1           .
160 1           .
161 1           .
162 1           .
163 1           .
164 1           .
165 1           .
166 1           .
167 1           .
168 1           .
169 1           .
170 1           .
171 1           .
172 1           .
173 1           .
174 1           .
175 1           .
176 1           .
177 1           .
178 1           .
179 1           .
180 1           .
181 1           .
182 1           .
183 1           .
184 1           .
185 1           .
186 1           .
187 1           .
188 1           .
189 1           .
190 1           .
191 1           .
192 1           .
193 1           .
194 1           .
195 1           .
196 1           .
197 1           .
198 1           .
199 1           .
200 1           .
201 1           .
202 1           .
203 1           .
204 1           .
205 1           .
206 1           .
207 1           .
208 1           .
209 1           .
210 1           .
211 1           .
212 1           .
213 1           .
214 1           .
215 1           .
216 1           .
217 1           .
218 1           .
219 1           .
220 1           .
221 1           .
222 1           .
223 1           .
224 1           .
225 1           .
226 1           .
227 1           .
228 1           .
229 1           .
230 1           .
231 1           .
232 1           .
233 1           .
234 1           .
235 1           .
236 1           .
237 1           .
238 1           .
239 1 -.003631074
240 1 -.002085845
241 1 -.006522712
242 1  .002849518
243 1   -.0024905
244 1   .00367562
245 1  .000116491
246 1  -.00245067
247 1  .000749183
248 1 -.000203197
249 1 -.000801834
250 1  .000653891
251 1 -.000147365
252 1  .001484411
253 1 -.002455185
254 1 -.000204286
156 2           .
end
format %tq time
label values PANELID PANELID
label def PANELID 1 "Austria 1", modify
label def PANELID 2 "Austria 2", modify

My first thought was to remove observations that are greater or equal to 0 and are not missing values.

bys PANELID: drop if ret>= 0 & ret!=.

So I end up with an unbalanced dataset with missing date observations.

input float(time PANELID ret)
156 1           .
157 1           .
158 1           .
159 1           .
160 1           .
161 1           .
162 1           .
163 1           .
164 1           .
165 1           .
166 1           .
167 1           .
168 1           .
169 1           .
170 1           .
171 1           .
172 1           .
173 1           .
174 1           .
175 1           .
176 1           .
177 1           .
178 1           .
179 1           .
180 1           .
181 1           .
182 1           .
183 1           .
184 1           .
185 1           .
186 1           .
187 1           .
188 1           .
189 1           .
190 1           .
191 1           .
192 1           .
193 1           .
194 1           .
195 1           .
196 1           .
197 1           .
198 1           .
199 1           .
200 1           .
201 1           .
202 1           .
203 1           .
204 1           .
205 1           .
206 1           .
207 1           .
208 1           .
209 1           .
210 1           .
211 1           .
212 1           .
213 1           .
214 1           .
215 1           .
216 1           .
217 1           .
218 1           .
219 1           .
220 1           .
221 1           .
222 1           .
223 1           .
224 1           .
225 1           .
226 1           .
227 1           .
228 1           .
229 1           .
230 1           .
231 1           .
232 1           .
233 1           .
234 1           .
235 1           .
236 1           .
237 1           .
238 1           .
239 1 -.003631074
240 1 -.002085845
241 1 -.006522712
243 1   -.0024905
246 1  -.00245067
248 1 -.000203197
249 1 -.000801834
251 1 -.000147365
253 1 -.002455185
254 1 -.000204286
156 2           .
157 2           .
158 2           .
159 2           .
160 2           .
161 2           .
162 2           .
end
format %tq time
label values PANELID PANELID
label def PANELID 1 "Austria 1", modify
label def PANELID 2 "Austria 2", modify

The question is: Can I delete all the PANELIDs with missing date observations at this point or is there a more efficient and easier way to do it in the first place?

Thank you in advance!

Christos

[Nick Cox]

Note that

 
 bys PANELID: drop if ret>= 0 & ret!=.

has the same effect as

  
 drop if ret>= 0 & ret!=.

I don't follow your question. No dates are missing, but some are absent. Isn't that an unsurprising consequence?

If you want to drop entire panels you need something different, namely something like

bys PANELID : egen bad_count = total(ret >= 0 & ret < .) 
drop if bad_count

although I don't follow why the missing values are any use.

[Christos Tzomakas]

Thank you for the quick response!