Experimental Design

Aim: to investigate, outline the purpose, mention variables

Variables: any factor you have to consider within an investigation

• Independent: variable we change on purpose

• Dependant: variable that changes because of the independent (measure)

• Controlled: variable that kept constant to prevent it affecting the results

• Uncontrolled: variable that is not kept constant as it will not affect results (by accident don’t control, other times its by design)

Hypothesis:

• 1 statement - prediction - educated guess

• both independent and dependent mentioned and linked

Experimental group: experience the independent variable

Control group: don’t experience independent variable

Method:

1. collect equipment

2. setup equipment

3. detailed enough to repeat

4. replicates (multiple trials)

   • record data in table

   • Calculate average

Results: table - calculate average - graph (line, column)

Line: dependant variable on Y axis - use crosses

Column: dependant variable on Y axis - columns should have a space in between them (IV: words/description, numbers no decimals, numbers in range)

Conclusion:

• restate your hypothesis

• supported or not?

• data to prove (minimum 2 points)

Discuss/Evaluate:

• use scientific theory to explain what happened + why

• trends in data

• problem - talk about solution

Reliability: consistency of data - ex. 61bpm/65bpm/82bpm/62bpm

82bpm is the anomaly, either remove or retest

Accuracy: precision of results - ex. 100mL or 100.25/ ½ or 0.5

Validity: whether you tested what you intended to test (controlled variable

Different types of data

1. Primary

   • collected yourself

   • time consuming and expensive

   • done in real time

   • more reliable

2. Secondary

   • collected by others

   • quick + inexpensive

   • from the past

   • less reliable

Qualitative

• descriptive

• based on opinion

VS

Quantitative

• numerical

• based on fact