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# Chapter 2

### Understanding Psychology by Richard A. Kasschau, Ph.D.

Question | Answer |
---|---|

sample | the small group of participants, out of the total number available, that a researcher studies |

naturalistic observation | research method in which the psychologist observes the subject in a natural setting without interfering |

case study | research method that involves an intensive investigation of one or more participants |

survey | research method in which information is obtained by asking many individuals a fixed set of questions |

longitudinal study | research method in which data is collected about a group of participants over a number of years to assess how certain characteristics change or remain the same during development |

cross-sectional study | research method in which data is collected from groups of participants of different ages and compared so that conclusions can be drawn about differences due to age |

correlation | the measure of a relationship between two variables or sets of data |

hypothesis | an educated guess about the relationship between two variables |

variable | any factor that is capable of change |

experimental group | the group to which an independent variable is applied |

control group | the group that is treated in the same way as the experimental group except that the experimental treatment (the independent variable) is not applied |

self-fulfilling prophecy | a situation in which a researcher's expectations influence that person's own behavior, and thereby influence the participant's behavior |

single-blind experiment | an experiment in which the participants are unaware of which participants received the treatment |

double-blind experiment | an experiment in which neither the experimenter nor the participants know which participants received which treatment |

placebo effect | a change in a participant's illness or behavior that results from a belief that the treatment will have an effect, rather than the actual treatment |

statistics | the branch of mathematics cocerned with summarizing and making meaningful inferences from collections of data |

descriptive statistics | the listing and summarizing of data in a practical, efficient way |

frequency distribution | an arrangement of data that indicates how often a particular score or observation occurs |

normal curve | a graph of frequency distribution shaped like a symmetrical, bell-shaped curve; a graph of normal distribution |

central tendency | a number that describes something about the "average" score of a distributiion |

variance | a measure of difference, or spread |

standard deviation | a measure of variability that describes an average distance of every score from the mean |

correlation coefficient | describes the direction and strength of the relationship between two sets of variables |

inferential statistics | numerical methods used to determine whether research data support a hypothesis or whether results were due to chance |