Imagine that you were a participant in an experiment where you were asked to eat cookies and rate how much you liked each cookie on a scale from 1 to 5,
Imagine that you were a participant in an experiment where you were asked to eat cookies and rate how much you liked each cookie on a scale from 1 to 5, where higher ratings mean higher liking of the cookie. You are asked to eat an Oreo cookie and rate it and then eat a Chips Ahoy cookie and rate it. For this experiment, answer the questions below.
1. What is the independent variable (IV)? What are the levels of the IV?
2. Was the IV manipulated between-subjects or within-subjects? How do you know?
3. What is the dependent variable (DV)? What operational definition was used in this experiment?
4. What scale of measurement was used for the DV?
5. The IV was bivalent. Explain how you can make it multivalent.
7. Do you think the cookie experiment has more internal validity or external validity? Explain your answer.
The Process of Research in Psychology 5th Edition Chapter 5: Variables and Measurement in Research
Dependent Variables (1 of 6)
Scales of Measurement
Different measures allow for different questions.
Some more reliable than others.
Scale can constrain statistical tests.
Nominal, ordinal, interval, and ratio.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
2
LO 5-1: Describe the measurement used in research studies.
Dependent Variables
Scales of Measurement
Different measures allow different questions to be asked.
Some measures are more reliable than others.
Scale constrains the statistical tests used to analyze the data.
Primary scales of measurement: nominal, ordinal, interval, and ratio.
2
Dependent Variables (2 of 6)
Scales of Measurement
Nominal scales.
Nonordered categorical responses.
Measuring a persons mood, college majors, gender.
Responses do not involve numerical values.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
3
LO 5-1: Describe the measurement used in research studies.
Nominal Scales
Nominal scale: A scale of measurement where nonordered categorical responses are collected.
Examples: Measuring a person’s mood given set categories, students’ selectin of college majors, gender.
Responses do not involve numerical values, but frequency of the responses can quantified.
3
Dependent Variables (3 of 6)
Scales of Measurement
Ordinal scales.
Scale that contains ordering on a continuum.
Responses equally spaced on continuum.
Rating a mood, reporting frequency, ranking stimuli.
Do not involve numerical values, but frequency can be quantified.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
4
LO 5-1: Describe the measurement used in research studies.
Ordinal Scales
Ordinal scale: A scale of measurement that contains an ordering on a continuum.
Responses are not assumed to be equally spaced on the continuum.
Examples: Rating a mood from “not at all” to “very,” reporting how often a behavior occurs from “none” to “more than five times,” rank orderings of stimuli.
Responses do not involve numerical values, but frequency of the responses can quantified.
4
Dependent Variables (4 of 6)
Scales of Measurement
Interval and ratio scales.
Interval scale measures categories that are equally spaced.
Likert scale.
Ratio scale is a measurement that involves comparison between scores.
Reaction time, accuracy on a test.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
5
LO 5-1: Describe the measurement used in research studies.
Interval and Ratio Scales
Interval scale: A scale of measurement that involves numerical categories that are equally spaced.
Likert scale: A common interval scale where respondents are asked how much they agree or disagree with a statement on a 1–5 or a 1–7 scale.
Ratio scale: A scale of measurement that involves numerical measurements and allows a ratio comparison of values between individual scores.
Example: Score of 50 on a ratio scale is twice as high as 25, reaction time (the amount of time to complete a task), accuracy for a test.
Fahrenheit and Celsius have values of 0 that are not the coldest temperature possible (interval scale); Kelvin has an absolute zero (ratio scale).
5
Dependent Variables (5 of 6)
Validity and Response Scales
Measurement can affect validity.
Face validly is the indication that a scale measures what is intended.
Poor definition can result in inaccurate conclusions.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
6
LO 5-1: Describe the measurement used in research studies.
Validity and Response Scales
Measurement can affect validity (e.g., the more response choices, the more accurate the measurement).
Face validity: The surface-level indication that a scale seems to measure what a researcher believes it does.
If a poor operational definition of a concept is used, inaccurate conclusions from the data can result.
6
Dependent Variables (6 of 6)
Validity and Response Scales
Example of measuring anxiety in children.
Questionnaires likely to have low validity.
Scores will likely provide poor definition of mood.
Nonverbal scale could be possible solution.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
7
LO 5-1: Describe the measurement used in research studies.
Example: Measuring anxiety in children who are 5 years old.
Questionnaires are likely to be inaccurate and lower validity.
Scores on the BAI will likely provide a poor operational definition of mood for children and lower construct validity.
Possible solution is a nonverbal scale (a survey response scale that involves picture responses for participants).
7
Independent Variables (1 of 5)
Independent variable is manipulated by researchers to test hypothesis.
Two types of manipulation.
Between-subjects.
Within-subjects.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
8
LO 5-2: Identify the independent and dependent variables included in an experiment.
Independent Variables
Independent variable: A variable in an experiment that is manipulated by researchers, and a comparison of the scores in the levels of the independent variable test the hypothesis.
Two types of manipulation:
Between-subjects: A manipulation in which each participant receives only one level of the independent variable and are typically randomly assigned to the different levels of between-subjects variables.
Within-subjects: A manipulation in which each participant receives all levels of the independent variable so that each participant serves as their own comparison, providing good control of individual differences because it removes participant differences from the comparison across conditions.
8
Independent Variables (2 of 5)
Types of Manipulations
Presence/Absence variables test the effect of the presence versus absence of something.
Bivalent independent variables are another name.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
9
LO 5-2: Identify the independent and dependent variables included in an experiment.
Types of Manipulations
Presence/Absence variables: Variables that typically involve manipulation of two levels—one is the presence of something (experimental group) and the other is the absence of that thing (control group).
Bivalent independent variables: another name for presence/absence variables—independent variables that contain only two levels.
9
Independent Variables (3 of 5)
Types of Manipulations
Type variables include different types of things being compared.
Dependent variable compared across each type.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
10
LO 5-2: Identify the independent and dependent variables included in an experiment.
Type variables: Variables that include a different type of the “something” being compared on the dependent variable (e.g., different types of drugs compared for a score on a depression questionnaire).
The dependent variable measured for each level is compared across the different types.
10
Independent Variables (4 of 5)
Types of Manipulations
Amount variables manipulate amounts of a factor in different levels.
Multivalent variable has three or more levels.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
11
LO 5-2: Identify the independent and dependent variables included in an experiment.
Amount variables: Variables that involve a manipulation of the amount of a factor in each level (e.g., optimal dosage for relieving symptoms).
Multivalent variable: An independent variable with three or more levels.
11
Independent Variables (5 of 5)
Quasi-Independent Variables
Variable that allows for comparison of groups based on nonmanipulatable characteristics.
Relationship between quasi-independent and dependent variables can be unclear.
Study that compares different age groups on memory tasks.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
12
LO 5-2: Identify the independent and dependent variables included in an experiment.
Quasi-Independent Variables
Quasi-independent (subject) variable: A variable that allows researchers to compare groups of participants based on characteristics that are not able to be manipulated.
Researchers must be cautious when drawing conclusions because the causal relationship between the quasi-independent and dependent variables is not always as clear as it is with true independent variables.
Example: A study that compares different age groups on completion of a memory task to determine if memory declines as people age.
12
Validity and Sources of Bias (1 of 9)
Effects on Internal Validity
Well-designed tests have higher validity.
Best design controls biases that make relationships less clear.
Confounding variables are extra factors outside of independent and dependent.
Conducting study on effects of video games on spatial abilities.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
13
LO 5-3: Evaluate a study design for possible sources of bias.
Validity and Sources of Bias
Effects on Internal Validity
Well-designed experiments typically have higher internal validity.
The best way to design a good experiment is to control biases that can make the causal relationship less clear.
Confounding variables: Extra factors outside of the independent and dependent variables that can make the causal relationship and results less clear.
Example: Conducting a study on the effects of video game playing on spatial abilities.
13
Validity and Sources of Bias (2 of 9)
Effects on Internal Validity
Experimenter bias.
Occurs when researcher treats groups differently based on hypothesis.
In single-blind design, the participants do not know what group they are in.
In double-blind design, neither participants nor researches know group assignments.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
14
LO 5-3: Evaluate a study design for possible sources of bias.
Experimenter Bias
Experimenter bias: A source of bias that occurs when a researcher inadvertently treats groups of participants differently in the study based on the researcher’s knowledge of the hypothesis for the study.
Example: An instructor gives one section of her class the old assignment and a new one to another section.
Single-blind design: An experimental design in which the participants do not know which participants are assigned to the different groups.
Double-blind design: An experimental design in which both the participants and the researchers who interact with the participants do not know which participants are assigned to the different groups.
14
Validity and Sources of Bias (3 of 9)
Effects on Internal Validity
Testing effects.
Occurs when participants are tested multiple times.
More likely when participants receive all levels.
Counterbalancing randomly assigns order of levels.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
15
LO 5-3: Evaluate a study design for possible sources of bias.
Testing Effects
Testing effects: Sources of bias that occur when participants are tested more than once or complete a task over a series of trials.
More likely to occur for independent variables where participants receive all levels than variables that use different groups.
Counterbalancing: An experimental control for testing effects in which the order of the levels of an independent variable are randomly assigned.
15
Validity and Sources of Bias (4 of 9)
Effects on Internal Validity
Regression toward the mean.
When participants score an extreme high or low score but regress toward mean in other tests.
Can hide variable effects.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
16
LO 5-3: Evaluate a study design for possible sources of bias.
Regression toward the Mean
Regression toward the mean: A source of bias that occurs when participants obtain an extreme score (high or low) on a questionnaire or task at one testing session but regress toward their mean score at another testing session; signifies extreme scores are not likely to recur.
Can hide an effect of a variable.
16
Validity and Sources of Bias (5 of 9)
Effects on Internal Validity
Regression toward the mean.
Can be minimized.
Random assignment to conditions.
Repetitions of the test.
Trimming extreme scores.
Splitting based on high and low scores.
Using large number of participants.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
17
LO 5-3: Evaluate a study design for possible sources of bias.
Can be minimized in a study by:
Random assignment to conditions.
Several repetitions of the test.
Trimming of extreme scores from data (when possible).
Splitting a group in half, based on high and low scores.
Using a large number of participants.
17
Validity and Sources of Bias (6 of 9)
Effects on External Validity
Degree to which a study measures realistic behaviors.
Attrition/Mortality affects participants decisions not to complete a study.
More control can decrease external validity.
Field experiments are conducted in a natural environment.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
18
LO 5-3: Evaluate a study design for possible sources of bias.
Effects on External Validity
External validity—The degree to which a study measures realistic behaviors and results can be generalized beyond the study.
Attrition/Mortality: A source of bias where participants decide not to complete a study, reducing the representativeness of the sample and reducing external validity.
More control can reduce internal validity but decrease external validity.
Field experiment: An experiment that is conducted in a naturalistic environment (e.g., in the “field”).
18
Validity and Sources of Bias (7 of 9)
Effects on External Validity
Hawthorne effect.
Source of bias in which the virtue of being studied can change behavior.
Landsberger’s study on workers in Western Electric Company.
Demand characteristics lead to participants changing behavior based on perceived purpose of study.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
19
LO 5-3: Evaluate a study design for possible sources of bias.
The Hawthorne Effect
Hawthorne effect: A source of bias in which by the simple virtue of being studied, participants’ behavior changes.
Landsberger’s study (1955) on workers in the Western Electric Company.
Demand characteristics: Sources of bias that occur when participants in a study attempt to “figure out” the purpose of the study and change their behavior based on their view of the purpose of the study.
19
Validity and Sources of Bias (8 of 9)
Effects on External Validity
Hawthorne effect.
Demand characteristics can occur as a result of involvement.
Hawthorne effect can be minimized.
Unobtrusive natural observation.
Anonymous responses.
Deception to hide study’s purpose.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
20
LO 5-3: Evaluate a study design for possible sources of bias.
Demand characteristics are related to the Hawthorne effect, as they occur as a result of a participant’s involvement.
Can be minimized in a study by:
Unobtrusive (naturalistic) observation.
Anonymous responses.
Deception to hide the purpose of the study.
20
Validity and Sources of Bias (9 of 9)
Sources of Bias Specific to Field of Study
Some biases are specific to certain fields.
Examples include:
Study-test time delay in memory research.
Visual acuity in visual-perception experiments.
Survey responses can be affected by social desirability.
McBride, The Process of Research in Psychology 5th Edition. © 2024 SAGE Publishing.
21
LO 5-3: Evaluate a study design for possible sources of bias.
Sources of Bias Specific to a Field of Study
Some sources of bias are specific to a field of study.
Examples:
Memory research where study–Test time delay can become a source of bias if it is not a variable of interest.
Visual acuity is often controlled for in visual-perception experiments.
Survey responses can be affected by social desirability bias, so many include items to help researchers exclude participants who are prone to this bias.
21
Collepals.com Plagiarism Free Papers
Are you looking for custom essay writing service or even dissertation writing services? Just request for our write my paper service, and we'll match you with the best essay writer in your subject! With an exceptional team of professional academic experts in a wide range of subjects, we can guarantee you an unrivaled quality of custom-written papers.
Get ZERO PLAGIARISM, HUMAN WRITTEN ESSAYS
Why Hire Collepals.com writers to do your paper?
Quality- We are experienced and have access to ample research materials.
We write plagiarism Free Content
Confidential- We never share or sell your personal information to third parties.
Support-Chat with us today! We are always waiting to answer all your questions.
