Sociologists use four major research designs: surveys, observation, experiments, and existing sources. The advantages and limitations of each of the four major research designs are as follows. A survey is a study, generally in the form of an interview or questionnaire, which provides researchers with information about how people think and act. The main advantages of surveys are less expensive, surveys can be sent by email, mail or over the phone, and surveys are useful in describing the characteristics of a large population. Some limitations with using surveys are that a lot of research must be conducted to develop questions relevant to the needed information and surveys are not as flexible as other means because the initial study design has to remain unchanged. An example of survey is sent via email or the end of class surveys that we take. Observation is a way to collect information through direct participation and by closely watching a group or community. Some advantages of observation are it allows sociologists to examine certain behaviors and communities that could not be investigated through other research techniques and observation can be the only way to gain certain types of information. Some limitations of observation are the observer must not become attached to the people he or she observes and it becomes hard to maintain confidentiality. An example of an observation is ethnography which is the study of an entire social setting through extended systematic observation. An experiment is an artificially created situation that allows a researcher to manipulate variables. Some advantages of experiments are direct measures of people’s behavior and experiments are the only means by which cause and effect can be established. Some limitations of experiments are ethical limitations on the degree to which subject’s behavior can be manipulated and most experiments are conducted in laboratories and do not always represent real life situations. An example of an experiment is the deliberate manipulation of people’s behavior. Existing sources are previously collected and publicly accessible information and data. Some advantages of existing resources are tends to be nonreactive and it does not influence people’s behavior and researchers can avoid the Hawthorne affect by using secondary analysis. An example of existing resources is census data compiled by the government. Some limitations of existing sources are if the researcher who relies on data collected by someone else may not find exactly what is needed.