ACT Science Flashcards: Evaluating And Modeling Experiments

What this deck covers

This deck focuses on Evaluating And Modeling Experiments, 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 does a high standard deviation indicate about a data set?

Answer: Data points are spread out over a wide range. Values are far from the average, showing variability.

Flashcard 2: What is a placebo?

Answer: An inactive substance or treatment given to the control group. Controls for psychological effects of treatment expectation.

Flashcard 3: Which type of error is due to random fluctuations in measurements?

Answer: Random error. Unpredictable variations that cannot be controlled.

Flashcard 4: What is the best interpretation of a best-fit line on a scatterplot?

Answer: It approximates the overall trend relating the two variables. Shows the general relationship despite individual data scatter.

Flashcard 5: Which type of study prevents placebo effects?

Answer: Double-blind study. Prevents bias from both subjects and researchers.

Flashcard 6: Find the slope if $y$ increases from $2$ to $8$ when $x$ increases from $1$ to $4$.

Answer: $m = 2$. Slope = $\frac{\text{rise}}{\text{run}} = \frac{8-2}{4-1} = 2$

Flashcard 7: What is an experimental group?

Answer: The group that receives the treatment or condition being tested. Allows comparison with control to measure treatment effects.

Flashcard 8: Identify the error in this experiment: No control variables used.

Answer: Introduce control variables to maintain constant conditions. Control variables prevent confounding of results.

Flashcard 9: What is the independent variable in an experiment measuring plant growth with different fertilizers?

Answer: Type of fertilizer. This is what the researcher changes or manipulates.

Flashcard 10: What should be measured: 'Effects of fertilizer on plant height'?

Answer: Plant height. The outcome variable affected by fertilizer treatment.

Flashcard 11: Identify the confounding variable if light differs between groups in a plant-growth study.

Answer: Light level. This uncontrolled factor could affect plant growth results.

Flashcard 12: Correct the experimental design: Results affected by confounding variables.

Answer: Identify and control confounding variables. Eliminates alternative explanations for observed effects.

Flashcard 13: What is the difference between correlation and causation?

Answer: Correlation is association; causation requires a direct effect. Causation means one variable directly influences another.

Flashcard 14: Identify the variable that is measured in an experiment.

Answer: Dependent variable. This responds to changes in the independent variable.

Flashcard 15: What is the role of peer review in scientific research?

Answer: To evaluate and validate research findings. Experts check research quality before publication.

Flashcard 16: What is a confounding variable?

Answer: An external variable affecting both independent and dependent variables. Third variable that influences both measured variables.

Flashcard 17: What is the range of the data set: 4, 7, 1, 9, 3?

Answer:

1. Largest minus smallest value: 9 - 1 = 8.

Flashcard 18: What should be constant: Testing effect of light on plant growth?

Answer: Soil type, water, and temperature. Controls for variables other than light intensity.

Flashcard 19: Identify the independent variable: Sugar concentration vs. Fermentation rate.

Answer: Sugar concentration. The factor deliberately varied to test effects.

Flashcard 20: Define a confounding variable.

Answer: An extraneous variable that affects the outcome of an experiment. Creates alternative explanations that invalidate results.

Flashcard 21: Which option best describes a negative correlation between $x$ and $y$?

Answer: As $x$ increases, $y$ decreases. Variables move in opposite directions from each other.

Flashcard 22: Identify the dependent variable if temperature is set and reaction rate is measured.

Answer: Reaction rate. This variable responds to changes in temperature.

Flashcard 23: What is a constant in an experiment?

Answer: A factor that does not change throughout the experiment. Remains unchanged to isolate variable effects.

Flashcard 24: Choose the independent variable: Time of day vs. Sleep quality.

Answer: Time of day. The factor researchers control and manipulate.

Flashcard 25: What is the dependent variable in an experiment?

Answer: The measured response that depends on the independent variable. This is what you measure to see the effect of changes.

Flashcard 26: What is a hypothesis in the context of an experiment?

Answer: A testable prediction about how the independent variable affects the dependent variable. States the expected relationship between variables.

Flashcard 27: What is the $y$-intercept in a linear model $y = mx + b$?

Answer: $b$, the value of $y$ when $x = 0$. Shows where the line crosses the vertical axis.

Flashcard 28: What is the role of peer review in scientific research?

Answer: To evaluate and validate research findings. Experts check research quality before publication.

Flashcard 29: What is the primary reason for conducting a pilot study?

Answer: To test feasibility and refine methodology. Small trial run identifies problems before main study.

Flashcard 30: What is the dependent variable in an experiment?

Answer: The variable that is measured or observed in response to changes. It's the effect that researchers measure for changes.

Flashcard 31: Identify the type of error that occurs when a measurement is consistently off by the same amount.

Answer: Systematic error. Consistent bias in one direction affects all measurements.

Flashcard 32: What is a repeated measures design?

Answer: An experimental design where the same subjects are used in all conditions. Reduces individual differences as confounding variables.

Flashcard 33: Identify a method to reduce bias in an experiment.

Answer: Use randomization to assign subjects to groups. Ensures equal chance of assignment to any group.

Flashcard 34: What does 'statistically significant' mean in experimental results?

Answer: Results unlikely due to chance, suggesting a real effect. Low probability the results occurred by random chance.

Flashcard 35: What is the purpose of a literature review in research?

Answer: To survey existing research and identify gaps. Examines previous studies to build research foundation.

Flashcard 36: What is the $y$-intercept in a linear model $y = mx + b$?

Answer: $b$, the value of $y$ when $x = 0$. Shows where the line crosses the vertical axis.

Flashcard 37: Which type of graph is best for comparing categories?

Answer: Bar graph. Best for discrete categories or groups.

Flashcard 38: What is replication in experimental design?

Answer: Repeating trials or experiments to check consistency of results. Confirms results are reliable and not due to chance.

Flashcard 39: Use $y = 2x + 1$ to find $y$ when $x = 4$.

Answer: $y = 9$. Substitute $x = 4$: $y = 2(4) + 1 = 9$

Flashcard 40: In a graph, what does the y-axis typically represent?

Answer: The dependent variable. Shows what researchers measure as the outcome.

Flashcard 41: What is the operational definition of a variable?

Answer: The exact procedure used to measure or define the variable. Makes the measurement method clear and repeatable.

Flashcard 42: Identify the main goal of experimental modeling.

Answer: To simulate and analyze real-world processes to make predictions. Creates testable representations of complex systems.

Flashcard 43: Identify the type of error that occurs when a measurement is consistently off by the same amount.

Answer: Systematic error. Consistent bias in one direction affects all measurements.

Flashcard 44: Select the dependent variable: Fertilizer amount vs. Crop yield.

Answer: Crop yield. The outcome measured in agricultural experiments.

Flashcard 45: Which method is used to ensure random assignment in an experiment?

Answer: Randomization. Eliminates bias by randomly assigning subjects.

Flashcard 46: Find $b$ in $y = mx + b$ if $m = 3$ and the line passes through $(2, 11)$.

Answer: $b = 5$. Substitute point into $y = mx + b$: $11 = 3(2) + b$, so $b = 5$.

Flashcard 47: Identify whether estimating $y$ at $x = 10$ is extrapolation if data span $x = 1$ to $5$.

Answer: Extrapolation. Estimating beyond the observed data range is extrapolation.

Flashcard 48: Identify the confounding variable if light differs between groups in a plant-growth study.

Answer: Light level. This uncontrolled factor could affect plant growth results.

Flashcard 49: Use $y = 5 - x$ to find $x$ when $y = 1$.

Answer: $x = 4$. Substitute $y = 1$: $1 = 5 - x$, so $x = 4$

Flashcard 50: What does it mean if a graph shows a linear relationship between variables?

Answer: The variables change at an approximately constant rate. Data points form a straight line pattern.

Flashcard 51: What is the independent variable in an experiment?

Answer: The variable that is manipulated or changed by the experimenter. It's the cause that researchers control to test effects.

Flashcard 52: Identify the control group in an experiment testing a new drug's effectiveness.

Answer: Group receiving placebo. This group receives no treatment for comparison.

Flashcard 53: What is a confounding variable?

Answer: An uncontrolled factor that can affect the dependent variable. Can create misleading results by affecting the outcome.

Flashcard 54: What is the difference between systematic error and random error?

Answer: Systematic shifts results consistently; random varies unpredictably. Systematic error is predictable; random error is not.

Flashcard 55: What does it mean if an experiment is 'replicable'?

Answer: It can be repeated with similar results. Other researchers get consistent results using same methods.

Flashcard 56: Identify the dependent variable if temperature is set and reaction rate is measured.

Answer: Reaction rate. This variable responds to changes in temperature.

Flashcard 57: Which option best supports causation: randomized experiment or observational study?

Answer: Randomized experiment. Random assignment allows causal conclusions to be drawn.

Flashcard 58: What is the best interpretation of a best-fit line on a scatterplot?

Answer: It approximates the overall trend relating the two variables. Shows the general relationship despite individual data scatter.

Flashcard 59: Identify the flaw: Results based on a small sample size.

Answer: Increase the sample size for more reliable results. Larger samples reduce random error and increase validity.

Flashcard 60: What does an outlier represent in a data set?

Answer: A data point far from the overall pattern or trend. May indicate measurement error or unusual conditions.

Flashcard 61: What does a correlation coefficient of 0 indicate?

Answer: No linear relationship between variables. Variables are completely independent of each other.

Flashcard 62: Correct the conclusion: 'Data supports hypothesis' with one trial.

Answer: Conduct multiple trials to ensure reliability. Single trials cannot establish reliable patterns.

Flashcard 63: Identify the relationship if points cluster around a horizontal line as $x$ increases.

Answer: No correlation (approximately constant $y$). Horizontal pattern shows $y$ doesn't change with $x$.

Flashcard 64: Choose the independent variable: Time of day vs. Sleep quality.

Answer: Time of day. The factor researchers control and manipulate.

Flashcard 65: Find the error in this hypothesis: 'Plants grow faster in the dark.'

Answer: Specify measurable variables like growth rate and light condition. Hypothesis lacks measurable, operational definitions.

Flashcard 66: Identify the relationship if points trend downward from left to right on a scatterplot.

Answer: Negative correlation. Downward trend indicates negative relationship between variables.

Flashcard 67: Identify the independent variable: Water temperature affects fish activity.

Answer: Water temperature. The factor being deliberately manipulated by researchers.

Flashcard 68: Which variable is manipulated to test its effect on another variable?

Answer: Independent variable. The researcher controls and changes this factor.

Flashcard 69: Which type of bias occurs when the sample is not representative of the population?

Answer: Sampling bias. Sample doesn't accurately reflect the target population.

Flashcard 70: What is a double-blind experiment?

Answer: Neither participants nor researchers know assigned groups. Prevents bias from expectations affecting results.

Flashcard 71: Which option is the correct conclusion if only the independent variable changes across trials?

Answer: Differences in results can be attributed to the independent variable. Only the treatment varies, so it caused any differences.

Flashcard 72: What term describes a factor that is kept constant to prevent influence on the outcome?

Answer: Controlled variable. These factors must remain constant to ensure valid results.

Flashcard 73: What does it mean if an experiment is repeatable?

Answer: The results can be consistently replicated under the same conditions. Demonstrates reliability and validity of findings.

Flashcard 74: Which option is the correct conclusion if only the independent variable changes across trials?

Answer: Differences in results can be attributed to the independent variable. Only the treatment varies, so it caused any differences.

Flashcard 75: What is the primary function of a hypothesis?

Answer: To provide a basis for experimental testing. Creates testable predictions for experiments to verify.

Flashcard 76: What does a p-value indicate in hypothesis testing?

Answer: Probability of observing results as extreme as the observed. Lower p-values suggest results are not due to chance.

Flashcard 77: Which group receives a placebo?

Answer: Control group. Controls for psychological treatment effects.

Flashcard 78: Correct the experimental design: Results affected by confounding variables.

Answer: Identify and control confounding variables. Eliminates alternative explanations for observed effects.

Flashcard 79: Identify the control group if plants get fertilizer A, fertilizer B, or no fertilizer.

Answer: The no-fertilizer group. This group receives no treatment for comparison.

Flashcard 80: What is the purpose of a hypothesis in an experiment?

Answer: To propose a testable explanation or prediction. It guides the experiment and can be tested.

Flashcard 81: What is the primary goal of data analysis in experiments?

Answer: To interpret and draw conclusions from data. Extract meaningful patterns and relationships from results.

Flashcard 82: Which phase of the scientific method involves testing a hypothesis?

Answer: Experimentation. Controlled tests determine if hypotheses are supported.

Flashcard 83: What does a p-value indicate in hypothesis testing?

Answer: Probability of observing results as extreme as the observed. Lower p-values suggest results are not due to chance.

Flashcard 84: Identify the flaw: Results based on a small sample size.

Answer: Increase the sample size for more reliable results. Larger samples reduce random error and increase validity.

Flashcard 85: What does it mean if an experiment is 'replicable'?

Answer: It can be repeated with similar results. Other researchers get consistent results using same methods.

Flashcard 86: Identify the error: No randomization in group assignment.

Answer: Use randomization to assign subjects to groups. Eliminates selection bias in experimental design.

Flashcard 87: Find the flaw: Experiment without a hypothesis.

Answer: Develop a testable hypothesis to guide the experiment. Hypotheses provide direction and focus for research.

Flashcard 88: Identify the error: No randomization in group assignment.

Answer: Use randomization to assign subjects to groups. Eliminates selection bias in experimental design.

Flashcard 89: What is the slope in a linear model $y = mx + b$?

Answer: $m$, the change in $y$ per unit change in $x$. Shows how steep the line is and direction of change.

Flashcard 90: Identify the independent variable if temperature is set and reaction rate is measured.

Answer: Temperature. The experimenter controls this variable to test its effect.

Flashcard 91: What is the purpose of a double-blind study?

Answer: To prevent bias by keeping both subjects and experimenters unaware of group assignments. Eliminates expectation bias from all participants.

Flashcard 92: What does it mean if a graph shows a linear relationship between variables?

Answer: The variables change at an approximately constant rate. Data points form a straight line pattern.

Flashcard 93: Define a confounding variable.

Answer: An extraneous variable that affects the outcome of an experiment. Creates alternative explanations that invalidate results.

Flashcard 94: Define a control group in an experiment.

Answer: A group that does not receive the experimental treatment. Provides baseline comparison to show treatment effects.

Flashcard 95: What is a sample size?

Answer: The number of observations or subjects in an experiment. Larger sizes increase reliability and statistical power.

Flashcard 96: What is interpolation when using a graph or model?

Answer: Estimating within the range of observed data. Predictions are more reliable within the data range.

Flashcard 97: What should be constant: Testing effect of light on plant growth?

Answer: Soil type, water, and temperature. Controls for variables other than light intensity.

Flashcard 98: What does it mean if results are statistically significant?

Answer: The observed effect is unlikely due to random chance alone. The probability of getting this result by chance is very low.

Flashcard 99: What is a constant in an experiment?

Answer: A factor that does not change throughout the experiment. Remains unchanged to isolate variable effects.

Flashcard 100: What is a sample size?

Answer: The number of observations or subjects in an experiment. Larger sizes increase reliability and statistical power.