Experimental design
64 flashcards covering Experimental design for the ACT Science section.
Experimental design is the structured way scientists plan and carry out experiments to test ideas reliably. At its core, it involves deciding what factors to change (called independent variables), what outcomes to measure (dependent variables), and how to control other influences that could skew results. This approach ensures experiments are fair and reproducible, helping to build trustworthy evidence for scientific claims.
On the ACT Science section, experimental design appears in questions that require you to analyze data tables, graphs, or descriptions of experiments, often asking you to identify variables, evaluate methods, or predict results based on setups. Common traps include confusing correlation with causation or overlooking uncontrolled variables, so focus on spotting flaws in procedures and understanding how changes affect data. Always identify the control group first to grasp the experiment's baseline.
Terms (64)
- 01
Independent Variable
The factor that is deliberately changed in an experiment to test its effect on the outcome.
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Dependent Variable
The factor that is measured or observed in an experiment to see how it responds to changes in the independent variable.
- 03
Controlled Variable
A factor that is kept constant throughout an experiment to ensure that it does not influence the outcome and allows for a fair test.
- 04
Control Group
The group in an experiment that does not receive the treatment or change, serving as a baseline for comparison with the experimental group.
- 05
Experimental Group
The group in an experiment that is subjected to the treatment or change being tested, allowing researchers to observe its effects.
- 06
Hypothesis
A testable statement or prediction about the relationship between variables in an experiment, based on prior knowledge or observations.
- 07
Null Hypothesis
A statement in an experiment that assumes there is no effect or relationship between variables, used to test if results are due to chance.
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Prediction
A specific forecast of what will happen in an experiment based on a hypothesis, often including expected outcomes for variables.
- 09
Experiment
A controlled procedure designed to test a hypothesis by manipulating variables and observing the results to draw conclusions.
- 10
Observation
The act of gathering data through the senses or instruments during an experiment to record what happens under specific conditions.
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Data
The information collected from an experiment, which can be quantitative or qualitative, and is used to analyze patterns and support conclusions.
- 12
Sample Size
The number of subjects or items included in an experiment, which affects the reliability and generalizability of the results.
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Replication
The process of repeating an experiment multiple times or by different researchers to verify results and reduce the impact of errors.
- 14
Randomization
The technique of assigning subjects to groups randomly in an experiment to minimize bias and ensure fair representation.
- 15
Bias
A systematic error in an experiment that skews results, often due to flawed design, preconceptions, or unequal treatment of groups.
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Validity
The extent to which an experiment accurately measures what it intends to measure, free from confounding factors that could invalidate results.
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Reliability
The consistency of results when an experiment is repeated under the same conditions, indicating that the methods are dependable.
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Accuracy
How close experimental measurements are to the true value, reflecting the precision of the tools and methods used.
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Precision
The degree to which repeated measurements in an experiment are consistent with each other, regardless of their accuracy.
- 20
Mean
The average value of a set of data points in an experiment, calculated by summing all values and dividing by the number of values.
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Median
The middle value in a sorted list of data points from an experiment, used as a measure of central tendency that is less affected by outliers.
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Mode
The most frequently occurring value in a set of data from an experiment, helping to identify the most common result.
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Trend
A pattern or direction in data from an experiment, such as increasing or decreasing, that indicates a relationship between variables.
- 24
Correlation
A statistical relationship between two variables in an experiment, where changes in one are associated with changes in the other.
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Causation
A direct link where one variable causes a change in another, which must be inferred carefully in experiments to avoid confusion with correlation.
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Placebo
An inactive substance or treatment given to a control group in an experiment to test the psychological effects of the real treatment.
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Double-Blind Study
An experimental design where neither the subjects nor the researchers know which group is receiving the treatment, reducing bias.
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Variables
The factors in an experiment that can change and affect the outcome, including independent, dependent, and controlled types.
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Constants
Factors in an experiment that remain unchanged to isolate the effects of the independent variable on the dependent variable.
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Procedure
The step-by-step method outlined in an experiment to ensure consistency and allow others to replicate the study.
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Materials
The tools, substances, or equipment used in an experiment, which must be listed to enable accurate replication.
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Results
The raw or processed data obtained from an experiment, presented through tables, graphs, or summaries for analysis.
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Conclusion
The interpretation of experimental results in relation to the hypothesis, drawing inferences about the variables' relationships.
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Graph Interpretation
The skill of analyzing graphs from experiments to identify trends, relationships, and anomalies in the data.
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Table Reading
The ability to extract and interpret information from data tables in experiments, such as comparing values across conditions.
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Outlier
A data point in an experiment that differs significantly from others, potentially indicating error or a unique condition.
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Interpolation
Estimating values between known data points in an experiment, such as on a graph, to predict intermediate outcomes.
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Extrapolation
Extending trends from existing data in an experiment to predict values beyond the measured range, though with increased uncertainty.
- 39
Scientific Method
A systematic process involving observation, hypothesis formation, experimentation, and analysis to investigate natural phenomena.
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Theory vs. Hypothesis
A hypothesis is a testable idea, while a theory is a well-substantiated explanation of phenomena based on extensive evidence from experiments.
- 41
Qualitative Data
Non-numerical information gathered in an experiment, such as descriptions of color or texture, that provides context to observations.
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Quantitative Data
Numerical information collected in an experiment, such as measurements of length or temperature, that allows for statistical analysis.
- 43
Direct Relationship
A positive correlation in an experiment where one variable increases as the other increases, shown on a graph as an upward slope.
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Inverse Relationship
A negative correlation in an experiment where one variable increases as the other decreases, appearing as a downward slope on a graph.
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Positive Correlation
A relationship in experimental data where both variables change in the same direction, indicating they move together.
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Negative Correlation
A relationship in experimental data where one variable increases while the other decreases, showing an opposite trend.
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No Correlation
A lack of relationship in experimental data where changes in one variable do not affect the other, resulting in scattered points on a graph.
- 48
Scatter Plot
A graph used in experiments to display the relationship between two variables, with points representing data pairs to show patterns.
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Line Graph
A chart in experiments that connects data points with lines to illustrate trends or changes over time or another variable.
- 50
Bar Graph
A visual representation in experiments using bars to compare quantities across different categories or conditions.
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Pie Chart
A circular graph in experiments that shows proportions of a whole, such as percentages of data categories.
- 52
Experimental Error
Any deviation from the true value in experimental results, caused by factors like measurement mistakes or environmental variations.
- 53
Systematic Error
A consistent bias in experimental measurements that affects all data in the same way, often due to faulty equipment or methods.
- 54
Random Error
Unpredictable variations in experimental data that occur by chance, which can be reduced by increasing sample size or replication.
- 55
Confounding Variable
An extraneous factor in an experiment that correlates with both the independent and dependent variables, potentially skewing results.
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Operational Definition
A clear, precise description of how a variable is measured or manipulated in an experiment to ensure consistency and replicability.
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Peer Review
The process where experts evaluate an experiment's design and results before publication to ensure scientific validity and accuracy.
- 58
Ethical Considerations
Guidelines in experiments to protect subjects, such as obtaining consent and minimizing harm, ensuring responsible research practices.
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Statistical Significance
A measure in experiments that determines if results are likely due to the tested effect rather than random chance, often using p-values.
- 60
Data Analysis
The process of examining experimental data to identify patterns, calculate statistics, and draw meaningful conclusions about variables.
- 61
Hypothesis Testing
The method in experiments of using data to determine whether to accept or reject a hypothesis based on statistical evidence.
- 62
Controlled Experiment
An experiment where all variables except one are held constant to clearly establish cause-and-effect relationships.
- 63
Longitudinal Study
An experimental design that observes subjects over an extended period to track changes and identify long-term effects.
- 64
Cross-Sectional Study
An experiment that analyzes data from a population at a single point in time to compare variables across groups.