Cross Sectional Studies Flashcards
what are features of a cross sectional study
takes place at a single point in time
does not involve manipulating variables
considers several characteristics at once
analyses prevailing characteristic in given population
what is a cross sectional study used to estimate
prevalence of a specified outcome in a defined population
e.g for public health planning
what individual characteristics is collected data based on
exposure to risk factors
outcome information
why do we do a cross sectional study
used when the study purpose is descriptive,
often uses survey
often there is no prior hypothesis
what is the aim of cross sectional studies
describe population or subgroup with regards to outcome and set of risk factors
and to determine prevalence of specified outcome for population/subgroups at particular point in time
why are cross sectional studies limited
because only carried out at one point in time
give no indication of sequence of events so not possible to determine CAUSALITY
what does a repeated cross sectional study give
a pseudo-longitudinal study
where are the individuals chosen from
same sampling frame or a different one
what is an example of a cross-sectional study
british association for the study of community dentistry survey
5 y/o children examined annually, prevalence of dental caries recorded and monitored over time
what do the sample frame and response rate determine
how well results can be generalised to whole population
how can the selected sample be representative of the population
if it is selected using a random method
what are some techniques used to minimise non-response
telephone and mail prompting
second and third mailing surveys
letters stressing importance of replying
incentives - money?
how can a response become biased
a person could be more likely to respond if they have particular characteristics and this is biased if the characteristic is related to the probability of having the outcome
what is an example of how response rate and sampling can be biased
door to door interviews - response rate highest in elderly and unemployed
this is because these people are most likely to be at home and more likely to experience higher levels of disease
leads to biased results
is loss to follow up an issue in cross sectional studies
no
what is a cross sectional study good for
broad knowledge of subjects who do or do not have specified outcome
but important to have optimum response levels
what are advantages of cross sectional studies
inexpensive
done in short time span
can estimate prevalence of specified outcome - as the sample is taken from whole population
many outcomes and risk factors can be studied
useful for public health planning, understanding disease aetiology and generation of hypotheses
what are disadvantages of cross sectional study
not easy to infer causal associations
only presents situation at one point in time - may change
prevalence-incidence bias - for long-standing diseases risk factors associated with death will be under-represented
outline coronary heart disease as an example of cross sectional study
objective - compare coronary risk factors and prevalence in Indians, Pakistani,Bangladeshi + Europeans in Newcastle
age 27-74 years
what were the results of the coronary heart disease study
differences in SES, lifestyles and anthropometric measures and disease
poorest groups - bangladesh and pakistani
bangladeshi men had most risk factors
smoking common
south asians disadvantaged in wide range of factors
high proportion had diabetes
what were the conclusions about the coronary heart disease study
coronary artery risk if not uniform among south asians
previously thought south asians had lower levels of Coronary risk factors than europeans, this study showed this is incorrect
why may have those conclusions been made about the coronary heart disease study
from combining ethnic subgroups and studying a narrow range of risk factors
outline the risk taking behaviours study
being involved in military combat role has negative effect on risk taking behaviour - smoking drinking
self-report questionnaire to assess hazardous behaviour
1700 participants
what were the results of the risk taking behaviour study
deployment significantly associated with risky driving, smoking and physical violence
what were limitations of the risk taking behaviour study
risk taking behaviours were examined at a single time point - direction of causality cannot be determined
confounding effects cannot be taken into account - sociodemographic
self reported behaviours - social desirability bias
outline the HPV cross-sectional study
aim to examine young womens perception and acceptability of HPV vaccination in china
117 female undergraduates surveyed
what were the results of the HPV study
only 44% of participants willing to be vaccinated
low awareness about HPV and cervical cancer
intention to receive future vaccination associated with high level of knowledge about risk factors for cervical cancer
what conclusions were made from the HPV study
low awareness and knowledge among young chinese women about HPV vaccine
social and cultural factors may influence womens intentions regarding future vaccination
what is the summary about cross sectional studies
cheap
not time consuming
very applicable to wide range of things
but cant be used for causal inference
