3.5: Other Aspects of Measurement

• Range Effect

  The clustering of scores at one end of a measurement scale; ceiling and floor effects.
• Ceiling Effect

  The clustering of scores at the high end of a measurement scale, allowing little or no possibility of increases in value.
• Floor Effect

  The clustering of scores at the low end of a measurement scale, allowing little or no possibility of decreases in value.
• Artifact

  In the context of a research study, an external factor that could influence or distort measures. These threaten the internal and external validity of a measurement.
• Experimenter Bias

  Occurs when the measurements obtained in a study are influenced by the experimenter's expectations or personal beliefs regarding the outcome of the study.
• Rosenthal and Fode (1963) identified a variety of ways that an experimenter can influence a participant's behaviour. These are what?

  1. Paralinguistic cues.
  2. Kinaesthetic cues.
  3. Verbal reinforcement of expected or desired responses.
  4. Misjudgement of participants' responses in the direction of expected results.
  5. Not recording participants' responses accurately.
• What are two options we could use to limit experimenter bias and what do these options do?

  These options standardise or automate the study–they are blind experiments.

  1. Single-Blind: The researcher does not know the predicted outcome.
  2. Double-Blind: The researcher and the participants are unaware of the predicted outcome.
• Demand Characteristics

  Refers to any potential cues or features of a study that (1) suggest to the participants what the purpose is and (2) influence the participants to respond or behave in a certain way.
• Reactivity

  Participants' modifications of their natural behaviour in response to the fact that they are participating in a research study or the knowledge that they are being measured.
• There are four reactivity roles that participants often take on. What are they?

  1. Good Subject
  2. Negativistic Subject Role
  3. Apprehensive Subject Role
  4. Faithful Subject Role
• Good Subject

  The participants have identified the hypothesis of the study and are trying to produce responses that support the investigator's hypothesis.
• Negativistic Subject Role

  These participants have identified the hypothesis of the study and are trying to act contrary to the investigator's hypothesis.
• Apprehensive Subject Role

  These participants are overly concerned that their performance in the study will be used to evaluate their ability or personal characteristics.
• Faithful Subject Role

  These participants attempt to follow instructions to the letter and avoid acting on any suspicions they have about the purpose of the study.