Experiments and observation

Experiments change conditions; observation records what happens. Both can be useful, but they support different kinds of conclusions.

Lesson 2 of 33 parts Practice Flashcards

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Independent variable and Dependent variable

Objective: Explain independent variable and dependent variable, distinguish their meanings, and apply them to a described case.

Independent variable: An independent variable is the factor manipulated in an experiment. Dependent variable: A dependent variable is the measured outcome. Psychological research distinguishes a construct from the procedure used to measure it. Random sampling and random assignment serve different purposes. Experiments can support causal inference when design and execution address competing explanations; observational associations require more caution. Ethical protection, replication, and transparent reporting are part of scientific quality. One result is evidence to evaluate rather than automatic proof of a universal rule. Application: Researchers assign different practice schedules. This most directly illustrates independent variable. A study records correct answers on a later test. This most directly illustrates dependent variable.

Worked examples

Try itOriginal teaching scenario: Researchers assign different practice schedules. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Researchers assign different practice schedules. Step 2 — Recall the relevant idea: An independent variable is the factor manipulated in an experiment. Step 3 — Connect the observation to the idea: The scenario is an illustration of independent variable. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: A study records correct answers on a later test. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: A study records correct answers on a later test. Step 2 — Recall the relevant idea: A dependent variable is the measured outcome. Step 3 — Connect the observation to the idea: The scenario is an illustration of dependent variable. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

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Independent variable and Dependent variable

Objective: Explain independent variable and dependent variable, distinguish their meanings, and apply them to a described case.

Worked examples

Try itOriginal teaching scenario: Researchers assign different practice schedules. Which idea from this section does it most directly illustrate?Show answer

Try itOriginal teaching scenario: A study records correct answers on a later test. Which idea from this section does it most directly illustrate?Show answer

Random assignment and Random sampling

Objective: Explain random assignment and random sampling, distinguish their meanings, and apply them to a described case.

Random assignment: Random assignment allocates participants to conditions by chance. Random sampling: Random sampling selects participants from a population by a chance method. Psychological research distinguishes a construct from the procedure used to measure it. Random sampling and random assignment serve different purposes. Experiments can support causal inference when design and execution address competing explanations; observational associations require more caution. Ethical protection, replication, and transparent reporting are part of scientific quality. One result is evidence to evaluate rather than automatic proof of a universal rule. Application: A chance procedure assigns volunteers to two groups. This most directly illustrates random assignment. Researchers randomly select names from a defined population list. This most directly illustrates random sampling.

Worked examples

Try itOriginal teaching scenario: A chance procedure assigns volunteers to two groups. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: A chance procedure assigns volunteers to two groups. Step 2 — Recall the relevant idea: Random assignment allocates participants to conditions by chance. Step 3 — Connect the observation to the idea: The scenario is an illustration of random assignment. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: Researchers randomly select names from a defined population list. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Researchers randomly select names from a defined population list. Step 2 — Recall the relevant idea: Random sampling selects participants from a population by a chance method. Step 3 — Connect the observation to the idea: The scenario is an illustration of random sampling. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Confound and Observational study

Objective: Explain confound and observational study, distinguish their meanings, and apply them to a described case.

Confound: A confound provides an alternative explanation by varying with the factor being studied. Observational study: An observational study measures conditions without assigning the relevant exposure. Psychological research distinguishes a construct from the procedure used to measure it. Random sampling and random assignment serve different purposes. Experiments can support causal inference when design and execution address competing explanations; observational associations require more caution. Ethical protection, replication, and transparent reporting are part of scientific quality. One result is evidence to evaluate rather than automatic proof of a universal rule. Application: One study group also receives more sleep than the other. This most directly illustrates confound. Researchers record existing sleep habits and performance. This most directly illustrates observational study.

Worked examples

Try itOriginal teaching scenario: One study group also receives more sleep than the other. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: One study group also receives more sleep than the other. Step 2 — Recall the relevant idea: A confound provides an alternative explanation by varying with the factor being studied. Step 3 — Connect the observation to the idea: The scenario is an illustration of confound. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

Try itOriginal teaching scenario: Researchers record existing sleep habits and performance. Which idea from this section does it most directly illustrate?Show answer

Step 1 — Read the observation: Researchers record existing sleep habits and performance. Step 2 — Recall the relevant idea: An observational study measures conditions without assigning the relevant exposure. Step 3 — Connect the observation to the idea: The scenario is an illustration of observational study. Step 4 — Check the limit: This short scenario illustrates the concept; it does not establish every detail or exclude every other influence in a real situation.

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