Valid

Key Stage 4

Meaning

Validity is whether a method produces results which test the hypothesis.

About Validity

A valid experiment is one which tests the hypothesis posed.

An invalid experiment would be one which does not test the hypothesis.

An experiment may be made invalid by not using control variables as they may affect the results instead of the independent variable.

A conclusion may also be valid or invalid depending on whether the conclusion fits the results that were given.

Examples

Valid Experiment

Hypothesis - The extension of a spring is directly proportional to the force applied to the spring.

Method - Attach different known weights to the spring and measure the extension of the spring.

Invalid Experiment

Hypothesis - The extension of a spring is directly proportional to the force applied to the spring.

Invalid Method 1 - Attach different known weights to an elastic band and measure the extension of the elastic band.

Invalid Method 2 - Attach different known weights to the spring and measure the width of the spring.

Invalid Method 3- Pull the spring with the hands and measure the extension of the spring.

Invalid Method 4 - Attach different known weights each to a different spring and measure the extension of each spring.