Lecture 2- Experimental Design/Scientific Process

Biology 171

What is the definition of a Hypothesis

It is a testable, possible explanation for a natural phenomenon used to make predictions and motivate experiments, they are falsifiable

A prediction comes before or after a hypothesis?

After

Correlation is ___ Causation

NOT

What are the 3 characteristics of a well controlled experiment

• Alters only a single variable in the test-group

• Contains a negative control that is not changed

• Contains a positive control where a variable with a known effect is introduced (miracle grow)

What is the def of a Theory

Theories are overarching explanations that explain broad patterns in nature and are based on lots of evidence and has been tested by many people and are well supported.

What are 4 things that make a good experimental design

• Can be replicated and repeated

• ethical

• only manipulating one variable at a time

• large sample size

Why isnt there a negative control in medical treatments

Because it is unethical to withhold treatment from a person