Experimental Design

Question 1

Steps

Answer 1

Step 1: research question, hypotheses and variables

Step 2: design experimental set-up, controls and replication, collect data

Step 3: feedback, pilot experiments, re-design

Question 2

Step 1

Answer 2

Choose research question: feasible, interesting, novel, ethical and relevant

Create hypotheses: specific (H0 and H1)

Define variables: dependent and independent, constant and confounding (associated with independent but related to dependent)

Question 3

Step 2

Answer 3

Design experimental set-up: independent variable (single, factorial or full factorial) - selection of methods

Consider controls: negative (confirm results obtained are due to experimental variables and not uncontrolled) and positive (confirms the experiment works)
Replication: biological (various samples) and technical (repeated measures/protocol)
Pseudoreplication: treating as independent samples when they aren´t
Reproducible? data re-analysed =
Replicable? experiment repeated = but new data

Determine how to collect data
Data collection- human error/unconscious bias and error of equipment

Internal validity: degree of confidence that results of an experiment are not influenced by any factor
External validity: degree to which results of an experiment can be applied to world situations