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Self inflicted wounds or the result of a data meat axe?

I have received tables that purportedly represent citations issued, by the SDPD, for the period Jan 2015 through December 2015. It contains 103,109 Vehicle Code-related records. I have taken a mighty leap and concluded that these records are all the result of traffic stops. That is where the sense ceases.
Month
Year
Records
Computed
Citations
Actual
Citations
Difference
Projected
Stops
Multiplier
Percentage
Missing
Percentage
Cited
Jan-15
9133
5200
9040
-3840
16443
0.45023
73.85
56.94
Feb-15
10584
6462
9068
-2606
16494
0.45023
40.33
61.05
Mar-15
9676
5169
6899
-1730
12548
0.45023
33.47
53.42
Apr-15
10870
5991
7569
-1578
13767
0.45023
26.34
55.11
May-15
10700
5425
9469
-4044
17223
0.45023
74.54
50.7
Jun-15
10098
4482
7910
-3428
14387
0.45023
76.48
44.39
Jul-15
10017
4622
8387
-3765
15255
0.45023
81.46
46.14
Aug-15
9055
4688
10018
-5330
18222
0.45023
113.69
51.77
Sep-15
8047
4488
9163
-4675
16666
0.45023
104.17
55.77
Oct-15
8783
5373
10186
-4813
18527
0.45023
89.58
61.17
Nov-15
9638
6036
8043
-2007
14629
0.45023
33.25
62.63
Dec-15
8820
5348
7357
-2009
13381
0.45023
37.57
60.63
115421
63284
103109
-39825
187542
54.9767

Records, Computed Citations and related computations are produced from Vehicle Stop Data (VSD.) Actual Citations, as mentioned above, are said to come from a discrete are set of tables and databases (see CPRA 16-998.) Shocking and revealing are the instances where the actual citations exceed the number of stop records[1]. It is especially so since we know, from experience, that less than 60% of stops result in the issuance of a citation. Accordingly, from these averages, we may project mathematically and conclude that Vehicle Stop data entry or compliance rates are appalling low.  Projections suggest over 70,000 records are missing; a number in keeping with the radical and unexplained diminishment in data collection/entry first identified, and disclosed to you, in December 2014.



There is no need to attempt to understand why the counts, in citations, from the VSD tables are so massively different from the numbers fetched from the SDPD citation tables and databases (39825.) That is a fool’s errand and I have enough to run. So, I direct you instead to the key and other conclusions of the Cordner Report, and its caution, and conclusions that, for me, are intended to be admonitions, to you. I embed excerpts from them below as I recall my earlier communications, to some of you, regarding self-inflicted wounds and their usefulness.

.

The Cordner Report At page 1
Officers completed 121,013 vehicle stop forms in 2001, a 28% decrease from the previous year. This very substantial decrease raises serious questions about the validity of the vehicle stop data.

The Cordner Report At page 2

One division did have 3,000 more stops than citations, but another had 7,000 fewer stop forms than citations. Of particular concern, it would appear from the data that non-compliance in completing stop forms was a bigger problem in more ethnically-diverse and less-affluent divisions, possibly skewing the data.

And, again in the Cordner Report At page 2

Key Issues The substantial decrease in stop forms in 2001, and resulting concerns about the representativeness of the data, severely limit the confidence that can be placed in any findings and conclusions. The authors have tried to be cautious in interpreting the data.


Please feel free to re-use the above text, by substituting 2015 wherever 2001 appears. The difference is that you were forewarned.

Other issues related to these citations will be addressed in the coming week.


[1] See 2001-2002 Cordner Report, at page 2

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