Table 2

Samples sizes required for individual level scores to achieve 90% confidence intervals of ±10 points on estimated pass rates

No of cases with the condition required to calculate reliable indicator level scores
No of indicators requiring a sample of ⩽50 casesNo of indicators requiring a sample of 51–100 casesNo of indicators requiring a sample of >100 cases
URTI = upper respiratory tract infections; UTI = urinary tract infections; HRT = hormone replacement therapy.
Chronic conditions
    Acne5
    Allergic rhinitis4
    Asthma4614
    Coronary artery disease526
    Depression3216
    Diabetes725
    Dyspepsia/PUD223
    Hypertension2222
    Osteoarthritis22
    Total231877
Acute conditions
    Acute childhood diarrhoea143
    Acute low back pain3
    Headache7
    Otitis media11
    URTI – bronchitis3
    URTI – rhinitis1
    URTI – tonsillitis111
    UTI20
    Total3638
Preventive care
    Cervical screening15
    Family planning113
    Influenza immunisation7
    HRT32
    Pneumococcal immunisation16
    Hepatitis B immunisation14
    Total2627