I disagree with your findings. I ran the test with your data.
It output CPH 1 time, CXS 18 times..
I am giving you the actual random 5% of records by Group.



here is the actual content of table GroupPCTS

Code:
MyId
ESRInits
Rid
RandomId
xtrafield



1
AKB
96321
4610
244.090133666992



2
BJM
95949
2827
151.849746704102



3
BMK
95950
3827
100.151893615723



4
CPH
96122
5726
6.90073394775391



5
CXS
95495
9093
14.6378517150879



6
CXS
95500
4090
31.3403434753418



7
CXS
95494
8094
59.0409469604492



8
CXS
95492
6095
65.2644958496094



9
CXS
95503
7089
90.2090530395508



10
CXS
95508
2086
121.786003112793



11
CXS
95493
7094
136.262619018555



12
CXS
95498
2091
155.098434448242



13
CXS
95502
6089
157.141555786133



14
CXS
95507
1086
185.013122558594



15
CXS
95509
3085
211.912933349609



16
CXS
95499
3091
224.878479003906



17
CXS
95505
9087
245.053237915039



18
CXS
95501
5090
245.798736572266



19
CXS
95506
87
254.95915222168



20
CXS
95497
1092
257.197570800781



21
CXS
95496
93
282.301483154297



22
CXS
95504
8088
295.968719482422



23
CZH
96322
5609
43.9079933166504



24
JD	
95644
8006
115.169563293457



25
JDJ
97076
9168
123.373725891113



26
JLC
95679
2985
17.0142707824707



27
JLC
95683
6983
23.5452003479004



28
JLC
95681
4984
60.8729286193848



29
JLC
95639
3009
103.448173522949



30
JLC
95677
987
104.955215454102



31
JLC
95680
3985
120.832618713379



32
JLC
95676
9987
125.059425354004



33
JLC
95678
1986
139.980987548828



34
JLC
95682
5984
217.515914916992



35
JS	
95645
9005
297.350616455078



36
JSF
95635
9011
166.520248413086



37
KS	
95933
6837
252.89567565918



38
LB	
95606
28
6.36464977264404



39
LD	
94461
5699
0.96670389175415



40
LD	
94456
701
4.85638999938965



41
LD	
94442
6710
17.9507904052734



42
LD	
94445
9708
20.8797817230225



43
LD	
94444
8709
28.2127437591553



44
LD	
94459
3700
35.0213356018066



45
LD	
94441
5710
49.3245735168457



46
LD	
94451
5704
58.2015037536621



47
LD	
94447
1707
73.5067596435547



48
LD	
94440
4711
77.7887649536133



49
LD	
94455
9702
87.9422988891602



50
LD	
94446
707
109.803718566895



51
LD	
94439
3711
115.743324279785



52
LD	
94452
6704
145.16520690918



53
LD	
94449
3706
162.84782409668



54
LD	
94450
4705
211.902542114258



55
LD	
94457
1701
249.628036499023



56
LD	
94443
7709
293.621215820313



57
LD	
94448
2706
297.223083496094



58
LM	
96544
7479
204.300384521484



59
LW	
95829
2898
62.4016647338867



60
LW	
95918
1846
68.2588043212891



61
LW	
95641
5008
79.9157180786133



62
LW	
95831
4897
125.816986083984



63
LW	
95833
6895
141.159408569336



64
LW	
95926
9841
149.904724121094



65
LW	
95917
846
162.657775878906



66
LW	
95830
3897
163.802520751953



67
LW	
95851
4885
184.329971313477



68
LW	
95919
2845
246.774322509766



69
LW	
95832
5896
247.372467041016



70
MC	
96889
2277
66.4617233276367



71
MCW
95614
8024
126.868217468262



72
PDB
95893
6860
266.441009521484



73
RG	
96182
5691
139.882659912109



74
RPT
95928
1840
119.91194152832



75
SSQ
95929
2839
48.9865226745605



76
SXW
95617
1022
1.00768804550171



77
SXW
95636
11
1.97778940200806



78
SXW
95619
3021
20.0485458374023



79
SXW
95650
4002
122.298484802246



80
SXW
95616
22
126.047714233398



81
SXW
95653
7001
133.728866577148



82
SXW
95623
7018
141.367431640625



83
SXW
95651
5002
173.82763671875



84
SXW
95622
6019
176.953994750977



85
SXW
95642
6007
192.431015014648



86
SXW
95621
5019
210.239517211914



87
SXW
95649
3003
230.569839477539



88
SXW
95618
2021
248.521560668945



89
SXW
95624
8018
260.706481933594



90
SXW
95615
9023
263.939239501953



91
SXW
95620
4020
269.511779785156



92
SXW
95652
6001
295.344909667969



93
TRS
96066
9759
72.0014495849609



94
VU	
96455
8531
244.912490844727
I have a feeling you did not copy/use the proper qry sql.

Please post the contents in your GroupPCTS table, using the test data you provided to me.