Contents of the MONICA Population Survey Data Book (Previous) Sections 1-4 (Next) Section 6.1.
The detailed tables of the data book give results by 10-year age groups 25-34, 35-44, 45-54, 55-64, and 35-64. Age group 25-34 is reported only for the RUAs where this optional age group was investigated fully (see Section 8 of the report on age, date of examination and survey periods in the MONICA surveys (2)). For continuous variables the tables show the mean, standard error of the mean, standard deviation, 20th, 50th and 80th percentiles and the cumulative proportions for certain cut-off points. For categorical variables the percentages of the categories are shown. Information on the number of observations and records with missing data is given in each table.
The general rules for calculating the tables are given here:
The subjects were classified into 10-year age groups 25-34, 35-44, etc. according to the age in full years on the date of examination. If the year of birth or examination was unknown, the observation was excluded from the analysis and not reported even as missing data because the age group could not be determined. If the month was unknown, the day and month were replaced by 30 June. If only the day was unknown, it was replaced by 15. (See also the report on age, date of examination and survey periods in the MONICA surveys (2).)
The results for the 10-year age groups were calculated without age standardization, but for age group 35-64 they were standardized to the world standard population (4) with weights:
| Age group: | 35-44 | 45-54 | 55-64 |
| Weight: | 12 | 11 | 8 |
In earlier versions of the data book, additional weighting was applied for the RUs in the cases where the RUA consisted of more than one RU. The sampling fractions of the RUs were examined in Section 12 of the report on participation rates, quality of sampling frames and sampling fractions in the MONICA Surveys (3). It was found that RUs of nearly every RUA had almost equal sampling fractions. Therefore, no weighting of the RUs was applied for the current version of the data book.
| ui | standard population weight for age group i (i.e. u2=12/31, u3=11/31 and u4=8/31). Note that u2 + u3 + u4 = 1; |
| ni | number of observations in age group i; |
| n = n2 + n3 + n4 | total number of observations in age group 35-64 |
| xij | value of the individual observation; |
| wij = wi = ui/ni | individual weight for an observation. Note that the sum of the wij's over all observations in age group 35-64 equals one. |
The mean in age group i was calculated as
and its standard error as
.
The age standardized mean was calculated as
and its standard error as
.
The population standard deviation in age group i was estimated by
and the standard deviation in the age standardized population by
.
The proportions were calculated in the usual way, which is equivalent to the calculation of the mean values assuming:
| xij = | 1 if the observation is in the numerator |
| 0 if the observation is not in the numerator. |
Let x[1], ... , x[ni] be the observations of age group i in ascending order. The kth percentile in age group i was calculated as the x[j] for which
.
To calculate age standardized percentiles, all observations of age group 35-64 were pooled together and sorted in ascending order as x[1], ... , x[n]. Let w[1], ... , w[n] be the individual weights of the ordered observations. The age standardized kth percentile was calculated as the x[j] for which
,
where w[0] is defined to be zero.
Contents of the MONICA Population Survey Data Book (Previous) Sections 1-4 (Next) Section 6.1.