Mastering ACT Science: Data Interpretation Strategies

Independent Variable (IV)

The factor that is changed or controlled in a scientific experiment, typically plotted on the x-axis.

Dependent Variable (DV)

The factor being measured or tested in an experiment, typically plotted on the y-axis.

The Key/Legend

A box identifying what different lines or symbols represent in a graph.

Direct Variation (Positive Correlation)

As one variable increases, the other also increases; can be linear or exponential.

Linear Relationship

A type of direct variation where the graph forms a straight line, indicating a constant rate of change.

Exponential Relationship

A type of direct variation where the graph curves upward steeply, indicating an increasing rate of change.

Inverse Variation (Negative Correlation)

As one variable increases, the other decreases, often resulting in a downward curve.

No Correlation

The data points are scattered randomly or the line is flat, indicating no effect of IV on DV.

Interpolation

The estimation of a value within two known values in a sequence.

Extrapolation

Estimating a value by extending a known sequence of values beyond the known area.

Averaging

Finding the mean of a set of numbers; formula: Average = Sum of terms / Number of terms.

Difference

The change in a quantity; formula: Δy = yfinal - yinitial.

Percent Change

A measure of how much something has increased or decreased relative to its original value.

Identifying Extremes

Looking at the lowest and highest values in a data representation before translating.

Trend Check

Confirming if the data increase, decrease, or fluctuate when comparing different representations.

Constants

Elements that remain unchanged between different experiments.

Variables

Elements that change between different experiments or tests.

Causation vs. Correlation

The principle that correlation does not imply causation, meaning one does not predict the other.

Interpolation Logic