Planning, designing, performing and publishing animal experiments

Question 1

Good experimental design will help me to

Answer 1

• improve the quality of my scientific work
• get published in better journals
• save time and money
• use fewer animals

Question 2

On which (six) variables does the power analysis depend?

Answer 2

• group size
• relevant effect of treatment (signal)
• standard deviation (noise)
• desired power
• level of significance
• alternative hypothesis

Question 3

Types of experiments:

Answer 3

• pilot study
• exploratory experiments
• confirmatory experiments
• experiments to explore relationships between variables

Question 4

Objectives of pilot studies

Answer 4

• logistics - setup of experimental protocol
• to analyse effect of treatment
• to analyse variation (noise)
• determine size of experiment
• staff training

Question 5

Objectives of exploratory experiments

Answer 5

• develop hypotheses for further testing
• measure many outcomes
• data snoopign –> hypothesis testing
• should be confirmed in a controlled expeirment
• analysed in a ANOVA

Question 6

Objectives of confirmatory experiments

Answer 6

• is a comparison
• tests a null hypothesis
• subjects are randomised
• should, if possible, be blind
• need to be powerful - have high probability of detecting an effect

Question 7

Objectives of experiments to explore relationship between variables

Answer 7

• tests whether two variables are associated
• if so, the nature of that relationship

Question 8

Name three ways of randomisation

Answer 8

• completely randomised design (computer)
• randomised block design
• latin square design

Question 9

Characteristics of randomised block design

Answer 9

• deals with known (suspected) heterogeneity
• breaks up an experiment into mini experiments
• subsets of experimental units (animals) e.g. males and females, large and small etc.

(so that you don’t end up having all large or femal animals in one group)

Question 10

What are the properties of a well-planned experiment?

Answer 10

• have a clear specification of the aims of the experiment
• is unbiased
• is powerful
• has a wide range of applicability
• should be simple
• should be possible to statistically analyse