What are some of the features of a census?
- It refers to universal sources of information.
- The population sits between birth and death registration.
- A census refers to both households and people.
- It has a universal coverage and it occurs at regular intervals - every 10 years in the UK.
What can a census tell us?
- Population size
- Population structure e.g. service needs
- Population characteristics such as unemployment, overcrowding, lone pensioners, single parents etc.
- It allows the government to plan services.
What is population size and structure measured by?
- Births
- Deaths
- Migration
How do you calculate the crude birth rate?
The number of live births per 1,000 population.
What is the general fertility rate?
The number of live births per 1,000 females aged 15-44 years.
What is the total period fertility rate?
The average number of children that would be born to a hypothetic woman in her life.
What are some of the links between Crude Birth Rates (CBR), General Fertility Rates (GFR) and Total Period Fertility Rates (TPFR)?
- Low CBR is due to low GFR.
- High CBR is due to high GFR and a high proportion of 15-44 year olds in London.
- GFR is affected by Age Specific Fertility Rates (ASFR).
What are the determinates of fertility?
Fecundity = the physical ability to reproduce.
High sterilisation and hysterectomies will mean low fecundity.
Fertility = the realisation of this potential as births.
What are some factors that can effect fertility rates?
High sexual activity = high fertility.
High economic climate = high fertility.
High contraception = low fertility.
High abortion rate = low fertility.
What do crude birth rates tells us?
The impact of births on the size of the population.
What do general fertility rates tell us?
They compare the fertility of fertile female populations.
What do total period fertility rates tell us?
They compare the fertility of fertile females without being influenced by age group structure.
How do we calculate Crude Death Rate?
This is the number of deaths per 1,000 population.
How do we calculate age specific death rates?
This is the number of deaths per 1,000 in an age group.
How do we calculate the Standardised Mortality Ratio?
This compares the ‘observed’ number of deaths with the number of expected deaths if age-sex distribution of populations were identical.
What are some of the reasons for collecting mortality data?
- Classifying the causes of death
- Analysing patterns in mortality rates
- Identifying health problems
- Informing service needs.
What are some of the variable effecting population estimates and projections?
- Immigration (big issue at the moment!)
- Births
- Deaths
What are Population Estimates?
This is applying what is known about births, deaths and migration to the present.
What are population projections?
These are estimates about future populations. There are additional assumptions about births, deaths and migration in the future.
Why do population estimates and projections depend on?
- Migration
- Fertility Rates - remember that fertility is difficult to predict because it is determined by social behaviour.
How is healthcare information used to identify health and healthcare needs?
There are a few key questions that need to be answered, e.g.
- How common?
- How serious?
- How expensive?
Morbidity data is key to discovering health care needs.
NHS expenditure should map into the healthcare needs of the country.
How do you calculate a trend?
A trend involves a comparison of rates which require;
- A Numerator (TOP)
- A demoninator (BOTTOM)
Name some numerator and denominator errors.
Numerator errors;
- Death certification
- Disease diagnosis
- Classification or coding errors
Denominator errors;
- Population used
- Population definition
- Population count or estimate.
When you interpret healthcare data what are some of the things you should consider?
Chance (random variation)
Artefactual (systematic) errors - such as numerator errors and denominator errors.
Real phenomenon - ‘natural’ epidemiological causes and medical care affects.
If there is a dramatic chance consider mistakes before you think of it as a real phenomenon.
