Sampling
Each country follows the same general procedure for chart sampling and data collection.
Samples are generated according to the following methodology:
- A case list of active patients is developed, based on eligibility criteria determined specifically in each country
- The lists are sampled either randomly or systematically, either alphabetically or by medical record number, and then numbered, from 1 to the end
- Charts are randomly sampled using one of three methods: HEALTHQUAL software, random number generator (internet option), OR every "nth" case (manual)
- If the chart is not found, the following chart on the list is chosen. However, clinics are encouraged to locate missing charts.
Medical records or charts are then reviewed by the clinic team, which may include data managers, nurses or doctors depending on availability. Data entry personnel are trained in data collection methods and chart review. Abstraction forms are used for medical record review from which information is entered into the HEALTHQUAL software. Abstraction forms and software are tailored for each country. Data reports can be generated through the HEALTHQUAL software.
SAMPLING TABLE
| Population Size |
Sample Size for 90%
Confidence Interval |
Sample Size for 95%
Confidence Interval |
| 0-49 |
35 |
38 |
| 50-79 |
43 |
48 |
| 80-99 |
52 |
61 |
| 100-139 |
61 |
73 |
| 140-179 |
67 |
82 |
| 180-199 |
70 |
86 |
| 200-249 |
75 |
94 |
| 250-299 |
79 |
101 |
| 300-349 |
82 |
106 |
| 350-749 |
94 |
127 |
| 750-4999 |
105 |
146 |
| 5000 or more |
107 |
150 |
Sample sizes are calculated for a 95% confidence interval to achieve a margin of error of 0.8, i.e. a width of 1.6
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Stratification:
In some cases, the sample can be stratified as needeed according to the indicator definitions. Samples can be stratified by gender to account for gynecological indicators, by age for some pediatric indicators, or other relevant criteria.
For example, HIVQUAL-T pediatric samples are stratified by age, as some indicators apply only to specific age groups (e.g., HIV disclosure is only measured in patients > 10 years of age).
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