This webpage explains frequently used statistical terms used as well as lists data sources.


Age-standardised rates

Age-standardised rates are standardised to a standard WHO population age distribution, to allow for comparisons between populations with different age structures. Rates are suppressed when the count (cases) is < 20.

Crude rates

Crude rates represent the proportion of the population affected by a disease. They take into account the population size of the area and are calculated by dividing the number of people affected by the number of people in the population. Crude rates are suppressed when the count (cases) is < 5.

Confidence intervals

A confidence interval gives the range that the true value is likely to fall within. Generally, 95% confidence intervals are presented on Healthspace.

A small sample of the total population examined can result in a wide confidence interval between lower level (LL) and upper level (UL).

For survey data, 95% confidence intervals give the range that if we selected 100 different samples, we would expect the prevalence value to fall within the range 95% of the time.


Count is the number of cases meeting the condition of interest (i.e. the cases). Counts are suppressed <5 cases (typically).

Rate ratio (95% CI)

Rate-ratios are suppressed if either of the rates are suppressed. Age-standardised rate ratios with 95% confidence intervals. Age-standardised rates have been age-standardised to the WHO world standard population.

Statistics and methods

What is the difference between prioritised ethnic groups and total response ethnic groups?

Prioritised ethnic groups assign people who reported multiple ethnic groups to only one ethnic group, in the prioritised order: Māori, Pacific, Asian, European/Other.

Total response ethnic groups include everyone who identifies with that ethnic group. This means that the sum of the ethnic group populations will be greater than the total population.