DisComp Sample Size

DisComp Sample Size

Recommendation – sample 3,371 veterans each week to obtain an overall margin of error (MOE) of 2% for the Trust score

Assumptions

• 20% response rate

• 89% working email rate

• 30-day rolling proportions

• Weekly sampling cadence

MTM Outpatient Quarantine Assumptions – based on previous review of DicComp population

The population counts used for sampling were adjusted to account for quarantine effects from the MTM Outpatient surveys. The final weekly population size was estimated to be 51,275 veterans.

	% veterans excluded by quarantine
Total	9.10%
Filing Only	8.37%
Vendor Scheduling Only	7.76%
Vendor Exams Only	4.98%
VHA Scheduling Only	13.21%
trVHA Exams Only	14.74%
Notification Only	9.46%
Multiple Events	8.64%

Two sampling strategies were examined

1. Reach an overall target level of precision for the Trust score: MOE = 2%

2. Obtain 10 respondents per stratum

Table 1 shows that, while providing a smaller fielded sample size, the MOE is increased for the 10-respondent strategy. Furthermore, targeting a MOE = 2% only samples 6.57% of the weekly popultion

Table 1. Overall sample strategy comparison

	Overall MOE = 2%	10 Responses Per Stratum
MOE	0.02	0.04
Total sample size	2,401	700
Total weekly sample size	600	175
Total fielded sample size	13,489	3,933
total weekly fielded sample size	3,371	983
% of population fielded each week	6.57%	1.92%

Table 2 shows that targeting the overall MOE = 2% results in much smaller MOE’s for each of the stratum variables, suggesting a more precise estimate.

Table 2. Stratum variable sample comparison

	Overall MOE = 2%			10 Responses Per Stratum
	Target Sample Size	MOE	Weekly Fielded Sample Size	Target Sample Size	MOE	Weekly Fielded Sample Size
Gender
F	349	5.25%	493	350	5.24%	490
M	2,053	2.16%	2877	350	5.24%	490
Age Group
<= 29	337	5.34%	470	140	8.28%	196
30-39	553	4.17%	778	140	8.28%	196
40-49	495	4.40%	694	140	8.28%	196
50-59	443	4.66%	622	140	8.28%	196
60+	574	4.09%	806	140	9.8%	196
Event
Filing	498	4.39%	698	100	9.80%	140
Vendor Scheduling	451	4.61%	633	100	9.80%	140
Vendor Exams	284	5.82%	399	100	9.80%	140
VHA Scheduling	113	9.22%	158	100	9.80%	140
VHA Exams	172	7.47%	243	100	9.80%	140
Notification	634	3.89%	890	100	9.80%	140
Multiple Events	184	7.22%	256	100	9.80%	140

Table 3. Population and sample sizes for OMB

Gender	Age Group	Filing		Vendor Scheduling		Vendor Exams		VHA Scheduling		VHA Exams		Notification		Multiple Events
		Population	weekly fielded sample	Population	weekly fielded sample	Population	weekly fielded sample	Population	weekly fielded sample	Population	weekly fielded sample	Population	weekly fielded sample	Population	weekly fielded sample
F	<= 29	285	19	303	20	235	15	46	3	78	5	323	21	147	10
F	30 - 39	486	32	487	32	315	21	109	7	160	11	518	34	180	12
F	40 - 49	384	25	426	28	280	18	68	4	137	9	419	28	143	9
F	50 - 59	318	21	312	21	178	12	63	4	101	7	359	24	103	7
F	>= 60	117	8	92	6	50	3	29	2	40	3	156	10	38	2
M	<= 29	1100	72	1315	86	808	53	171	11	317	21	1477	97	567	37
M	30 - 39	1921	126	1971	130	1315	86	445	29	715	47	2356	155	858	56
M	40 - 49	1761	116	1877	123	1244	82	397	26	593	39	2179	143	662	44
M	50 - 59	1680	110	1611	106	983	65	411	27	598	39	2135	140	589	39
M	>= 60	2859	188	1529	101	897	59	726	48	1017	67	3943	259	763	50
Total		10911	698	9923	633	6305	399	2465	158	3756	243	13865	890	4050	256