Hypothesis and experimentation

The experimenter changes the duration of light so it is the independent variable. In exams identify the factor deliberately changed.

Plant height is measured as the outcome so it is the dependent variable. In exams treat the measured outcome as the dependent variable.

The amount of sugar should remain the same to isolate the effect of temperature. In exams change only one independent variable.

A clear hypothesis includes both the changed factor and a measurable outcome. In exams an if-then structure is useful.

Larger equal-sized groups reduce random effects. In exams look for repetition and adequate sample size to improve reliability.

Checking unexpected results and repeating the experiment are parts of science. In exams treat a hypothesis as a testable idea not a proven fact.

The effect of the new chemical must be compared with a group without it. In exams a control group provides a baseline comparison.

The number of nails lifted gives a quantitative indication of magnetic strength. In exams choose an outcome that is numerical and measurable.

Different species may naturally germinate differently and hide the true effect of salt. In exams identify confounding variables.

Using the same person and measurement method reduces other differences. In exams choose comparable conditions.

Widely varying repeated results indicate low reliability. In exams close results under the same conditions indicate reliability.

An error in the same direction for every measurement is a systematic error. In exams identify consistent instrument bias.

Validity means that the experiment measures the effect being investigated. In exams look for a direct link between the measurement and the hypothesis.

A null hypothesis generally states that there is no effect or difference. In exams identify the no-difference statement.

Extra water could also affect growth so the cause is unclear. In exams identify any second factor changed at the same time.

Similar results obtained by different people show reproducibility. In exams distinguish repetition from reproduction.

Random selection reduces the chance of overselecting a particular type of sample. In exams identify methods that reduce bias.

Selecting only favorable evidence is confirmation bias and distorts conclusions. In exams scientific honesty requires recording all results.

An anomalous value should be investigated before being removed. In exams do not discard an outlier without justification.

Clear headings and consistent units make comparison accurate. In exams check that table headings include quantity and unit.

In a medicine trial expectations of participants and evaluators can influence results. In exams choose blinding when subjective effects are possible.

Changing both fabric and stain prevents isolation of the soap's effect. In exams keep other factors constant for a fair comparison.

A scientific hypothesis must be falsifiable so evidence could potentially show it to be wrong. In exams look for both testability and falsifiability.

An automatic sensor reduces human reaction delay. In exams improved instruments can reduce measurement error.

Once treated the control group no longer provides an unbiased baseline. In exams keep the control group free from the tested factor.