Controlled Experiment


However, in many cases those same researchers provide direction about what points readers may want to consider, but hesitate to make any broad conclusions or statements. Transferability takes into account the fact that there are no absolute answers to given situations; rather, every individual must determine their own best practices. Transferring the results of research performed by others can help us develop and modify these practices. However, it is important for readers of research to be aware that results cannot always be transferred; a result that occurs in one situation will not necessarily occur in a similar situation. Therefore, it is critical to take into account differences between situations and modify the research process accordingly.

The statistical validity speaks to whether the statistics conducted in the study support the conclusions that are made. This is referred to the extent to which an experiment is similar to real-life situations as the experiment’s mundane realism. Acquiescence refers to a tendency for examinees to agree with items regardless of their content. The pattern may result from an underlying examinee disinterest and lack of involvement, or from a desire simply to respond in the affirmative. One way to identify and potentially reduce acquiescence is to use both positively and negatively worded items.

Famous Faces uses pictorial stimuli integrated with verbal clues about famous people; whereas Information is a purely auditory-vocal task. Formal operational thought within the Crystallized domain can be assessed through Double Meanings. Double Meanings challenges examinees to unify apparently disparate semantic stimuli. KAIT subtests, Double Meanings and Definitions, can also provide follow-up to questionable performance on tasks of word knowledge and verbal concept formation, such as Wechsler’s Vocabulary or Similarities. Auditory Comprehension can be used for questions regarding an individual’s memory and comprehension ability.

In the scientific paradigm, the term refers to the use of hypotheses that can be tested using observation and experiment. Philosophically, empiricism defines a way of gathering knowledge by direct observation and experience rather than through logic or reason alone . Ethnographers spend extensive time in the setting being studied and use observations, interviews, and other analyses to understand the nature of the culture.

Because it is neither practical nor ethical to randomize people to variable housing conditions, this subject is difficult to study using an experimental approach. In another example, a well-known natural experiment in Helena, Montana, smoking was banned from all public places for a six-month period. Investigators later reported a 60-percent drop in heart attacks for the study area during the time the ban was in effect. The essential difference between internal goggles of revealing and external validity is that internal validity refers to the structure of a study and its variables while external validity relates to how universal the results are. They are both factors that should be considered when designing a study, and both have implications in terms of whether the results of a study have meaning. Both are not “either/or” concepts, and so you will always be deciding to what degree your study performs in terms of both types of validity.

These four big validities–internal, external, construct, and statistical–are useful to keep in mind when both reading about other experiments and designing your own. However, researchers must prioritize and often it is not possible to have high validity in all four areas. In Cialdini’s study on towel usage in hotels, the external validity was high but the statistical validity was more modest. This discrepancy does not invalidate the study but it shows where there may be room for improvement for future follow-up studies (Goldstein, Cialdini, & Griskevicius, 2008).

Some claim that the external validity of such an experiment is high because it is taking place in the real world, with real people who are more diverse than a typical university student sample. However, as real-world settings differ dramatically, findings in one real-world setting may or may not generalize to another real-world setting. The only way to be certain that the results of an experiment represent the behaviour of a particular population is to ensure that participants are randomly selected from that population. Samples in experiments cannot be randomly selected just as they are in surveys because it is impractical and expensive to select random samples for social psychology experiments. It is difficult enough to convince a random sample of people to agree to answer a few questions over the telephone as part of a political poll, and such polls can cost thousands of dollars to conduct.

Field surveys are non-experimental designs that do not control for or manipulate independent variables or treatments, but measure these variables and test their effects using statistical methods. Field surveys capture snapshots of practices, beliefs, or situations from a random sample of subjects in field settings through a survey questionnaire or less frequently, through a structured interview. The strengths of field surveys are their external validity , their ability to capture and control for a large number of variables, and their ability to study a problem from multiple perspectives or using multiple theories. More complex designs may include multiple treatment groups, such as low versus high dosage of the drug, multiple treatments, such as combining drug administration with dietary interventions. In a true experimental design , subjects must be randomly assigned between each group. If random assignment is not followed, then the design becomes quasi-experimental .

It can be defined as the extension of research findings and conclusions from a study conducted on a sample population to the population at large. While the dependability of this extension is not absolute, it is statistically probable. Because sound generalizability requires data on large populations, quantitative research — experimental for instance — provides the best foundation for producing broad generalizability. The larger the sample population, the more one can generalize the results. The empirical data that is collected from either of these methods has to be analyzed.