Scientific Method

• What is the scientific method

• Observation

• Compare to other experimental results

• If both do not agree?

• Consistent with predictions

• No; reject hypothesis and formulate a new hypothesis

• Similarities with learning?

• New information

• Compare to previous knowledge

• Different from prior knowledge?

• Reject prior or current information; seek out more information

Scientific Method

• A systematic way of learning about natural phenomena.

• Supported hypotheses

• Tentative?

• Why are hypotheses that have been previously supported falsified?

• How is a hypothesis falsified?

Scientific Method

• Observation: Objects that weight more seem to fall faster than objects that weight less.

• Example : rock and a feather

• Why? What factors are causing this apparent relationship?

• Hypothesis? The difference in speed is due to the heavier object accelerating more than the lighter object.

• Experiment: drop a rock off a building at the same time a feather is dropped.

• Time how long it takes both to fall

Scientific Method

• Experiment Anatomy

• Independent variable?: What variable was manipulated?

• What is different between each treatment?

• Mass

• Shape of object

• Aerodynamics of the object

• Dependent variable: how was the affect of the treatment measured?

• Distance / time = speed

Was that experiment the scientific method?

• Observation: What are the facts of the observation?

• Hypothesis: anything wrong ?

• Prediction:? Does it follow from the hypothesis?

• Experiment:

• Independent variable: ?

• Dependent variable: ?

• Other experimental factors constant between treatments?

Scientific Method

• Observation

• A rock weights more than a feather

• A rock will hit the ground first

• Does this mean the heavier rock fell faster than the lighter feather?

• Since acceleration is the result of gravity then is the acceleration due to gravity affected by the mass of an object?

• identify the factors that might be affecting the outcome of the natural occurrence

What is a testable hypothesis?

• a hypothesis has be falsifiable explanation

• A rock will fall faster than a feather

• Is this a hypothesis?

• A rock will accelerate as it falls from a given height.

Hypothesis:

• The hypothesis should describe the expected relationship between the observation and the independent variable: but not the actual experiment.

• What is the independent variable?

• The heavier objects fall faster because the acceleration due to gravity is increased as the mass of an object is increased.

Prediction:

• The prediction is based upon the experiment designed to test the hypothesis

• If a two balls that differ in mass are dropped from a given height the ball with the greater mass will arrive at the ground sooner than the lighter ball.

• The prediction includes the independent variable and the dependent variable of the experiment.

Experiment:

• If a two balls that differ in mass are dropped from a given height the ball with the greater mass will arrive at the ground sooner than the lighter ball.

• Independent variable? =

• Dependent variable? =

Experiment

• Factors to kept constant –

• Size and shape of the ball?

• Distance for each trial and treatment

• Angle of the ramp

Sample Size

• Repeated trials of the same experimental

procedure.

• Repeated trials of the same experimental

How many samples?

Data representation : Comparison of means

Data representation: Regression