Learn: In class Test Bio lab | Quizlet

Null hypothesis

statement assuming there is no effect, no difference, or no relationship between variables

Alternate hypothesis

A statement claiming that there is an effect, difference, or relationship between variables; it's what the researcher typically wants to find support for, and it is accepted if the null hypothesis is rejected.

Predictions

A specific, testable statement of the expected outcome of an experiment, usually written in an "If... then..." format

categorical variable

A variable that represents distinct groups or categories rather than numeric values (e.g., treatment group — Control vs. Aspirin).

continuous variable

A variable that represents numeric, measurable quantities that can take on a range of values (e.g., number of hairs, height, weight).

Control group

The group in an experiment that does not receive the treatment being tested

control group

The group in an experiment that does not receive the treatment or variable being tested, so its results can be compared against the control group.

Independent Variable

The variable that is deliberately changed or controlled by the experimenter to test its effect on something else; it's the "cause" in the experiment.

Ex. Giving them aspirin or a placebo

Dependent variable

The variable that is measured or observed in an experiment; it's the "effect" that changes in response to the independent variable.

Ex. If their hair grew, what the length is.

Controlled variables

A variable that is kept constant for all groups in an experiment so it doesn't affect the results.

Graph formatting

Proper graphs include labeled axes with axis titles and units, error bars, and a figure caption placed below the graph — but no title above the graph. A key/legend is only included when more than two groups are compared.

Hypothesis

A possible explanation for something you observed, based on the facts you already know. It's not proven true or false — it's an educated guess that you test through experimentation to see if it holds up.

mean

The average of a group of numbers

standard error

A measure of how much variability or spread there is among the individual data points within a group. It tells you how confident you can be that the mean is a good representation of the group.

Interpreting the P value

A number that shows the probability that your results happened by random chance rather than a real effect. A small p-value (≤ 0.05) means you reject the null hypothesis; a large p-value (> 0.05) means you fail to reject it.