A quantitative research:
A. Uses the analysis of numerical data
B. Involves large number of participants representative of the population of interest
C. Aims at using statistics to explain the observations
D. Uses various instruments to collect data (questionnaires, monitors, other tools)
Aqualitativeresearch:
A. Data are in the form of words, pictures, and objects
B. Involves small number of participants
C. Aims at providing a complete and detailed description
D. Researcher serves as data-gathering instrument
In a cross-sectional study,
A. Exposure and outcome are assessed at the same time, it is used to study the prevalence of diseases and risk factors in a population
B. Advantages: relatively quick, easy, and inexpensive, can study multiple exposures and outcomes
C. Disadvantages: temporal sequence and causal association between exposure and outcome cannot be established
D. Examples: Health Survey for England (UK) and National Health and Nutrition Examination Survey (NHANES in the US) are both being conducted as a series of cross-sectional examination
In a case-control study,
A. Subjects are selected on the basis of having a disease (cases, controls)
B. Groups are compared with respect to the proportion of having a history of exposure
C. Advantages: relatively quick and inexpensive; suitable for the evaluation of the diseases with long latent periods and for rare diseases; can assess multiple risk factors for a single disease
Disadvantages: cannot directly calculate the incidence of disease unless the study is population-based; difficult to establish temporal sequence and causal association between exposure and outcome;prone to recall bias; inefficient for rare exposures
A cohort study:
A. Can be prospective (disease has not occurred at the beginning of the study) and retrospective (disease has occurred at the time the study is initiated)
B. Subjects are selected on the basis of having the exposure and are followed up over time to assess the outcome; it is direct measurement of disease incidence
C. Advantages: can directly calculate the incidence of disease among exposed and non-exposed; can elucidate temporal relationship between exposure and outcome; bias in exposure assessment is minimized (prospective studies)
Disadvantages: expensive and time-consuming (especially if prospective); inefficient for rare diseases; requires availability of adequate records (retrospective); losses to follow-up may substantially affect the validity of the results
微信支付 
支付宝支付