Reliable statistics are needed for appropriate planning and/or proper decision making and as women's needs differ from those of men, sex-disaggregated statistics is needed. Women's issues will then be adequately covered in planning of development activities. For many years, statistics collected and analysed has been "gender blind". In population statistics, however, the distribution of the nation's population has been by sex and age group and presented in population pyramids, with the right side of the pyramid indicating the distribution of women and the left side indicating the distribution of men, both sides by age group. Through the population statistics, mortality rates by sex and life expectancy of women and men have been revealed. The "gender blind" statistics do, however, not decompose data according to sex but only provide an overall total. For example, the average income of workers in Tanzania (in Shilling) does not indicate how the average income is distributed within the population. Data on the specific income of female and male workers is needed for policy makers to take the right decisions. In general, gender-sensitive national statistics is produced when: (i) All sectors are gender mainstreamed; and (ii) Questionnaires are designed in such a way that the sex variable appears for every activity for which data is being collected.