ACT Science Flashcards: Experimental Design

What this deck covers

This deck focuses on Experimental Design, giving you a quick way to review the definitions, rules, and examples that matter most for ACT Science.

How to use these flashcards

Work through these flashcards in short sessions. Try to answer each prompt before flipping the card, then revisit any cards you miss until the explanation feels automatic.

Flashcard 1: What is a positive control in experimental design?

Answer: A condition known to produce an effect to verify the setup works. Verifies experimental system is functioning properly.

Flashcard 2: Which option best supports causation: manipulating light intensity or only observing natural light levels?

Answer: Manipulating light intensity. Manipulation allows testing cause-effect relationships.

Flashcard 3: Define the term 'sample size' in research.

Answer: The number of subjects included in a study. Larger samples generally provide more reliable and generalizable results.

Flashcard 4: Identify the purpose of a control group in an experiment.

Answer: To provide a baseline for comparison with the experimental group. Shows what happens without treatment for fair comparison.

Flashcard 5: Identify one advantage of a repeated measures design.

Answer: Reduces variability by using the same subjects. Each person serves as their own control.

Flashcard 6: State the purpose of a placebo in experiments.

Answer: To eliminate bias by mimicking the experimental treatment. It prevents participants from knowing if they received real treatment.

Flashcard 7: What is a quantitative measurement in data collection?

Answer: A numerical measurement with units. Provides precise, measurable data for analysis.

Flashcard 8: Identify the group that receives the treatment in an experiment.

Answer: Experimental group. This group gets the treatment being tested.

Flashcard 9: What strategy is used to minimize the placebo effect in an experiment?

Answer: Double-blind procedure. Neither group knows treatment status to prevent bias.

Flashcard 10: What is an operational definition in experimental design?

Answer: A variable definition stated in measurable, specific procedures. Ensures consistent, objective measurement methods.

Flashcard 11: What is double-blind procedure in an experiment?

Answer: Neither subjects nor evaluators know group assignments. Eliminates bias from both sides of study.

Flashcard 12: What is an operational definition in experimental terms?

Answer: A clear, precise description of how variables are measured. This ensures researchers measure variables consistently and objectively.

Flashcard 13: What is the primary purpose of keeping a control group?

Answer: To provide a baseline for comparison to the treatment condition. Shows what happens without the treatment.

Flashcard 14: What is a source of systematic error in an experiment?

Answer: A consistent bias that shifts measurements in one direction. Creates predictable deviation from true values.

Flashcard 15: Identify a key feature of quantitative data in experiments.

Answer: Numerical and can be measured. Allows statistical analysis and precise comparisons.

Flashcard 16: Which option best matches a negative control: a condition expected to produce no effect?

Answer: A condition expected to produce no response. Confirms no false positive responses occur.

Flashcard 17: What is the purpose of blinding in experiments?

Answer: To prevent bias from influencing results. When participants don't know their group, expectations can't skew results.

Flashcard 18: State one way to minimize bias in experiments.

Answer: Use of double-blind procedures. When neither group knows treatment status, expectations can't influence outcomes.

Flashcard 19: What is the significance level in hypothesis testing?

Answer: The probability of rejecting a true null hypothesis. It sets the threshold for determining statistical significance.

Flashcard 20: Which design change best controls a confounder: keep temperature constant or measure it once?

Answer: Keep temperature constant. Control eliminates temperature as confounding variable.

Flashcard 21: Identify the control group: drug trial compares drug vs sugar pill.

Answer: The sugar pill (placebo) group. No active treatment provides baseline comparison.

Flashcard 22: What is a 'between-subjects' design?

Answer: Different subjects are used in each condition. Separate groups reduce individual differences effect.

Flashcard 23: Find the independent variable: A study on exercise's effect on sleep quality.

Answer: Exercise. Exercise is the factor being manipulated to see its impact.

Flashcard 24: Which variable is the outcome or response variable in an experiment?

Answer: Dependent variable. This measures what happens due to treatment.

Flashcard 25: Which option best increases reliability: perform more trials or change the hypothesis?

Answer: Perform more trials. More trials average out random errors.

Flashcard 26: What is a source of systematic error in an experiment?

Answer: A consistent bias that shifts measurements in one direction. Creates predictable deviation from true values.

Flashcard 27: Identify the confounder: exercise group also changes diet, but diet is not tracked.

Answer: Diet change. Uncontrolled variable that affects the outcome.

Flashcard 28: What does it mean to 'operationalize' a variable in research?

Answer: To define it in practical, measurable terms. Makes abstract concepts concrete and testable.

Flashcard 29: What is an operational definition in experimental design?

Answer: A variable definition stated in measurable, specific procedures. Ensures consistent, objective measurement methods.

Flashcard 30: Define 'systematic error' in experimental design.

Answer: Consistent, predictable error that affects measurements. Unlike random error, systematic error creates consistent bias in one direction.

Flashcard 31: What is the purpose of random sampling in experiments?

Answer: To ensure that each member of the population has an equal chance of selection. Prevents selection bias in choosing participants.

Flashcard 32: Define the term 'sample size' in research.

Answer: The number of subjects included in a study. Larger samples generally provide more reliable and generalizable results.

Flashcard 33: Which option best matches a negative control: a condition expected to produce no effect?

Answer: A condition expected to produce no response. Confirms no false positive responses occur.

Flashcard 34: What is a positive control in experimental design?

Answer: A condition known to produce an effect to verify the setup works. Verifies experimental system is functioning properly.

Flashcard 35: Identify the best way to test one factor at a time when studying two variables.

Answer: Hold one variable constant while varying the other. Isolates effects of individual variables.

Flashcard 36: What is meant by 'random error' in experiments?

Answer: Error that varies unpredictably between measurements. Random error creates variability but doesn't consistently bias results.

Flashcard 37: Identify the independent variable: plants receive $0$, $5$, or $10$ mL fertilizer daily.

Answer: Daily fertilizer volume. The researcher controls fertilizer amount.

Flashcard 38: Define 'systematic error' in experimental design.

Answer: Consistent, predictable error that affects measurements. Unlike random error, systematic error creates consistent bias in one direction.

Flashcard 39: Identify a key feature of quantitative data in experiments.

Answer: Numerical and can be measured. Allows statistical analysis and precise comparisons.

Flashcard 40: What is the purpose of a pilot study?

Answer: To test the feasibility and refine the methodology. Small-scale trial identifies potential problems early.

Flashcard 41: What distinguishes qualitative from quantitative data?

Answer: Qualitative is descriptive; quantitative is numerical. Qualitative uses words/categories while quantitative uses numbers/measurements.

Flashcard 42: What is the advantage of using a factorial design in experiments?

Answer: Allows examination of interactions between variables. Tests multiple variables simultaneously for efficiency.

Flashcard 43: What is random error in an experiment?

Answer: Unpredictable variation that causes scatter in repeated measurements. Causes data points to spread around true value.

Flashcard 44: What distinguishes qualitative from quantitative data?

Answer: Qualitative is descriptive; quantitative is numerical. Qualitative uses words/categories while quantitative uses numbers/measurements.

Flashcard 45: What is the primary goal of experimental design?

Answer: To establish cause-and-effect relationships. Proves one variable directly causes changes in another.

Flashcard 46: What is a pilot study?

Answer: A small-scale preliminary study to evaluate feasibility. It tests procedures and identifies potential problems before the full study.

Flashcard 47: Identify the dependent variable: Studying the effect of light on photosynthesis.

Answer: Rate of photosynthesis. This is the measured response to different light conditions.

Flashcard 48: What is the role of statistical analysis in experimental design?

Answer: To determine the significance of results. Determines if results are due to chance or treatment.

Flashcard 49: Why is it important to have a large sample size in an experiment?

Answer: To increase the generalizability of results. Results apply more broadly with diverse samples.

Flashcard 50: What does 'replication' mean in scientific research?

Answer: Repeating an experiment to verify results. Confirms findings are consistent and reliable.

Flashcard 51: What is the primary goal of random sampling?

Answer: To ensure every individual has an equal chance of selection. This prevents sampling bias and increases representativeness.

Flashcard 52: Which method ensures that experimental results are not biased?

Answer: Randomization. Random assignment eliminates systematic differences.

Flashcard 53: State the purpose of a placebo in experiments.

Answer: To eliminate bias by mimicking the experimental treatment. It prevents participants from knowing if they received real treatment.

Flashcard 54: Which option best increases reliability: perform more trials or change the hypothesis?

Answer: Perform more trials. More trials average out random errors.

Flashcard 55: What is meant by 'external validity' in experiments?

Answer: The extent to which results generalize to other contexts. High external validity means results apply beyond the specific study conditions.

Flashcard 56: Identify a potential confounding variable: Studying the effect of sleep on memory.

Answer: Stress levels. Stress could independently affect memory, creating alternative explanations.

Flashcard 57: What is the effect of increasing sample size in an experiment?

Answer: Increases reliability and reduces sampling error. Larger samples better represent the target population.

Flashcard 58: Which method ensures that experimental results are not biased?

Answer: Randomization. Random assignment eliminates systematic differences.

Flashcard 59: Define 'placebo effect' in experimental terms.

Answer: Changes in outcomes due to participants' expectations. Believing you received treatment can cause real physiological changes.

Flashcard 60: Define 'null hypothesis' in research terms.

Answer: A statement that there is no effect or difference. It assumes no treatment effect exists until evidence proves otherwise.

Flashcard 61: Which aspect of an experiment is manipulated by the researcher?

Answer: Independent variable. The researcher controls this to test its effects.

Flashcard 62: Identify the group that receives the treatment in an experiment.

Answer: Experimental group. This group gets the treatment being tested.

Flashcard 63: Identify the control group: Testing a new medication vs. placebo.

Answer: Placebo group. The placebo group provides the comparison baseline for the medication group.

Flashcard 64: What is an experimental group?

Answer: The group receiving the treatment under investigation. This group receives the actual treatment being tested for effectiveness.

Flashcard 65: What is a confounding variable?

Answer: A variable that influences both independent and dependent variables. It creates alternative explanations for observed results.

Flashcard 66: What is blinding (single-blind) in an experiment?

Answer: Subjects do not know which treatment group they are in. Prevents placebo effects from biasing results.

Flashcard 67: Which aspect of an experiment is manipulated by the researcher?

Answer: Independent variable. The researcher controls this to test its effects.

Flashcard 68: What is the importance of an operational definition in research?

Answer: Defines how variables are measured and observed. Ensures consistent measurement across all studies.

Flashcard 69: What is random sampling, and what does it primarily improve?

Answer: Selecting subjects by chance; it improves population representativeness. Makes results generalizable to the population.

Flashcard 70: What is random assignment in experimental design?

Answer: Randomly allocating participants to different groups. This ensures groups are equivalent before treatment begins.

Flashcard 71: What is the main purpose of replication in experiments?

Answer: To confirm the reliability and validity of results. Repeated studies help establish whether findings are consistent and trustworthy.

Flashcard 72: What is a placebo in experimental design?

Answer: An inert treatment used to mimic the experimental treatment. Controls for psychological effects of treatment.

Flashcard 73: What is a controlled variable in an experiment?

Answer: A factor kept constant across all experimental conditions. These prevent confounding effects from other variables.

Flashcard 74: Which variable is the outcome or response variable in an experiment?

Answer: Dependent variable. This measures what happens due to treatment.

Flashcard 75: Identify the measurement type: recording mass as $12.4$ g.

Answer: Quantitative. Mass measurement provides numerical data.

Flashcard 76: Identify the variable measured in an experiment to assess the effect of manipulation.

Answer: Dependent variable. This shows the effect of the manipulation.

Flashcard 77: What is a confounding variable?

Answer: A factor that changes with the independent variable and affects outcomes. Makes it hard to determine true cause of results.

Flashcard 78: Which type of variable can potentially confound the results of an experiment?

Answer: Confounding variable. These create alternative explanations for results.

Flashcard 79: What kind of variable is manipulated to observe effects on the dependent variable?

Answer: Independent variable. This is what the researcher changes or controls.

Flashcard 80: Identify the best control for a drug study: compare to no treatment, placebo, or higher dose only.

Answer: Placebo. Placebo controls for psychological effects.

Flashcard 81: What is a 'confounding variable' in an experiment?

Answer: An extraneous variable that affects the outcome, obscuring results. Makes it impossible to determine true cause of results.

Flashcard 82: What does it mean if an experiment is 'controlled'?

Answer: Variables are regulated to prevent confounding effects. Eliminates alternative explanations for results.

Flashcard 83: What is a sample size, and why does it matter?

Answer: Number of subjects/observations; larger sizes reduce random error. More data points increase statistical reliability.

Flashcard 84: What is the advantage of using a factorial design in experiments?

Answer: Allows examination of interactions between variables. Tests multiple variables simultaneously for efficiency.

Flashcard 85: What can be concluded about causation from a correlational study?

Answer: Correlation does not establish causation. Association alone cannot prove one causes another.

Flashcard 86: What is the benefit of using a placebo in control groups?

Answer: To isolate the effect of the treatment itself. Separates psychological effects from actual treatment.

Flashcard 87: What is the role of statistical analysis in experimental design?

Answer: To determine the significance of results. Determines if results are due to chance or treatment.

Flashcard 88: Which option best increases precision: use a more sensitive instrument or add a placebo?

Answer: Use a more sensitive instrument. Better instruments reduce measurement uncertainty.

Flashcard 89: Identify the experimental group: Testing a new teaching method vs. traditional.

Answer: Group using the new teaching method. This group receives the new method being evaluated.

Flashcard 90: Define 'randomization' in the context of experimental design.

Answer: Assigning subjects to groups by chance to reduce bias. Ensures each participant has equal chance of any group.

Flashcard 91: Identify one advantage of a repeated measures design.

Answer: Reduces variability by using the same subjects. Each person serves as their own control.

Flashcard 92: What is a 'null hypothesis' in the context of an experiment?

Answer: A statement that there is no effect or difference. Assumes no relationship exists between variables.

Flashcard 93: What is a confounding variable?

Answer: A variable that influences both independent and dependent variables. It creates alternative explanations for observed results.

Flashcard 94: What is a dependent variable in an experiment?

Answer: A variable that is measured and affected in the experiment. This is the outcome or response being studied.

Flashcard 95: What is the dependent variable in an experiment?

Answer: The measured outcome that responds to the independent variable. This outcome is observed to see if it changes.

Flashcard 96: Define 'placebo effect' in experimental terms.

Answer: Changes in outcomes due to participants' expectations. Believing you received treatment can cause real physiological changes.

Flashcard 97: What is double-blind procedure in an experiment?

Answer: Neither subjects nor evaluators know group assignments. Eliminates bias from both sides of study.

Flashcard 98: What is an experimental group in an experiment?

Answer: A group that receives the treatment or manipulated condition. Used to test the effect of the treatment.

Flashcard 99: Which option is the clearest operational definition of "growth"?

Answer: Increase in height in cm over $7$ days. Specific, measurable criteria define the variable.

Flashcard 100: What is a pilot study?

Answer: A small-scale preliminary study to evaluate feasibility. It tests procedures and identifies potential problems before the full study.