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# MrsVanDyke Chapter 2

### Research Methods

Term | Definition |
---|---|

Scientific Method | A five-step process for empirical investigation of a hypothesis under conditions designed to control biases and subjective judgments |

Empirical Investigation | An approach to research that relies on sensory experience and observation as research data |

Theory | A testable explanation for a set of facts or observations |

Hypothesis | A statement predicting the outcome of a scientific study; a statement describing the relationship among variables in a study |

Operational Definitions | Specific descriptions of concepts involving the conditions of a scientific study; stated in terms of how concepts are to be measured or what operations are being employed to produce them |

Independent Variable (IV) | A stimulus condition so named because the experimenter changes it independently of all the other carefully controlled experimental conditions |

Random Presentation | A process by which chance alone determines the order in which the stimulus is presented |

Data | Pieces of information, especially information gathered by a researcher to be used in testing a hypothesis |

Dependent Variable (DV) | The measured outcome of a study; the responses of the subjects in a study |

Replicate | doing a study over to see whether the same results are obtained |

Experiment | A kind of research in which the researcher controls all the conditions and directly manipulates the conditions, including the independent variable |

Confounding Variables (Extraneous Variables) | Variables that have an unwanted influence on the outcome of an experiement |

Controls | Constraints that the experimenter places on the experiment to ensure that each subject has the exact same conditions |

Random Assignment | Each subject of the sample has an equal likelihood of being chosen for the experimental group of an experiment |

Ex Post Facto | Research in which we choose subjects based on a pre-existing condition |

Correlational Study | A type of research that is mainly statistical in nature |

Survey | A quasi-experimental method in which questions are asked to subjects (questions should not be skewed or biased toward a specific answer) |

Naturalistic Observation | A research method in which subjects are observed in their natural environment |

Longitudinal Study | A type of study in which one group of subjects is followed and observed for an extended period of time |

Cross-Sectional Study | A study in which a representative cross section of the population is tested or surveyed at one specific time |

Cohort-Sequential Study | A research method in which a cross section of the population is chosen and then each cohort is followed for a short perid of time |

Personal Bias | The researcher allowing personal beliefs to affect the outcome of a study |

Expectancy Bias | The researcher allowing his or her expectations to affect the outcome of a study |

Double-Blind Study | An experimental procedure in which both researchers and participants are uninformed about the nature of the independent variable being administered |

Institutional Review Board (IRB) | A committee at each institution where research is conducted to review every experiment for ethics and methodology |

Institutional Animal Care and Use Committee (IACUC) | A committee at each institution where research is conducted to review every experiment involving animals for ethics and methodology |

Frequency Distribution | A summary chart, showing how frequently each of the various scores in a set of data occurs |

Histogram | A bar graph depicting a frequency distribution. Height of bars indicates the frequency of a group of scores |

Descriptive Statistics | Statistical procedures used to describe characteristics and responses of groups of subjects |

Mean | Measure of central tendency most often used to describe a set of data. Calculated by adding all the scores and dividing by the number of scores |

Median | Measure of central tendency for a distribution, represented by the score that separates the upper half of the scores in a distribution from the lower half |

Mode | Measure of central tendency for a distribution, represented by the score that occurs more often than any other |

Range | The simplest measure of variability, represented by the difference between the highest and the lowest values in a frequency distribution |

Standard Deviation (SD) | Measure of variability that indicates the average difference between the scores and their mean |

Normal Distribution | A bell curve, describing the spread of a characteristic throughout a population |

Correlation | Relationship between variables, in which changes in one variable are reflected in changes in the other variable |

Correlation Coefficient | A number between -1 and +1 expressing the degree of relationship between two variables |

Inferential Statistics | Statistical techniques used to assess whether the results of a study are reliable or whether they might be simply the result of chance |

Random Sample | A sample group of subjects selected by chance |

Representative Sample | A sample obtained in such a way that it reflects the distribution of important variables in the larger population in which the researchers are interested; i.e., age, income level, ethnicity, etc... |

Significant Difference | Psychologists accept a difference between the groups as "real", or significant when the probability that it might be due to an atypical sample drawn by chance is less than 5 in 100 (indicated by the notation p<0.05) |