Practical research

• probability sampling - every member of the population has a chance of being selected.
• systematic - every member of the population is listed with a number, but instead of randomly generating numbers, individuals are chosen at regular intervals.
• simple random - every member of the population has an equal chance of being selected. your sampling frame should include the whole population.
• cluster - involves dividing population in to subgroup, but each subgroup shoud have the similar aracteristics to the whole sample. This method is good for dealing with large ang dispersed population.
• stratified - involves dividing the population into subpopulations that may differ in important ways. To use this sampling method, you divide the population into subgroup called (strata) based on the relevant characteristics ( gender, identity, age range, income bracket, job role).
• non-probability sample - individuals are selected based on non-random criteria, and not every individual has a chance of being included.
• non-probability sample - this type of sample is easier and cheaper to access, but it has a higher risk of sampling bias.
• quota - relies on the non random selection of a predetermined number or proportion of units.
• voluntary response - is mainly based on ease of access. Instead of the researcher choosing participants and directly contacting them, people volunteer themselves. (self selection bias)
• convenience - simply includes the individuals who happen to be most accessible to the researcher. convenience samples are at risk for both sampling bias and selection bias.
• snowball - if the population is hard to access, this sampling can be used to recruit participants.
• purposive - this type of sampling is also known as judgment sampling, involves the researcher using their expertise to select a sample that is most useful to the purposes of the research.
• experimenter effect - This threat appears when the characteristics of the researcher affect the behavior of the subjects or respondents.
• Hawthorne effect - This occurs when the respondents or subjects respond artificially to the treatment because they know they are being observed as part of a research study.
• measurement effect - It is also called the reactive effects of the pretest. It occurs when add subjects have been exposed to the treatment through taking the pretest. This exposure might affect the posttest results.
• Non-experimental research designs - include survey studies. In this type of research design, investigations are conducted through self-report. Surveys generally ask respondents to report on their attitudes, opinions, perceptions, or behaviors.
• Sample - a representative of the total population.
• Group - can be smaller than a mass.
• Mass - larger than a group.
• Retrospective- The dependent variable is identified in the present and an attempt is made to determine the independent variable that occurred in the past.
• Cross-sectional - The data are collected at a single point in time. The design requires subjects who are at different points, phases, or stages of an experience. The subjects are assumed to represent data collected from different time period.
• longitudinal - the researcher collects data from the same people at different times. Compared to the cross-sectional survey, this study is conducted over a longer period of time.
• Descriptive - This design is utilized for the purpose of accurately portraying a population that has been chosen because of some specific characteristics. The purpose is to provide a picture of a situation as it naturally happens.
• Comparative. This design is used to compare and contrast representative samples from two or more groups of subjects in relation to certain designated variables that occur in normal conditions.
• Correlational - The design is used to investigate the direction and magnitude of relationships among variables in a particular population.
• evaluative - This design involves making a judgement of worth or value. It allows the researcher to delineate, obtain and provide information that is useful for judging decision alternatives when conducting a program or service. It can be formative (process) or summative (outcome).
• face to face interaction - this is still the best method of survey due to its high rate of retrieval.
• selection bias - this results when the subjects or respondents are not randomly selected
• maturation - this happens when the experiment is conducted beyond a longer period of time during which most of the subjects undergo physical, emotional, and or psychological changes
• history - this refers to a threat to internal validity which happens during the conduct of the study when an unusual event effects the result of an experiment
• instrumentation change - the instrument used in gathering the data must not be changed or replace during the conduct of the study
• mortality - there is a threat to validity when one or more subjects die, dropout, or transfer as in the case of a student who has not completed his or her participation in the experiment
• testing - threat may occur in a study when a pretest is given to subjects who have knowledge of baseline data