Unit 3.3 - Reporting & Critical Evaluation

Question 1

What are the two types of variation?

Answer 1

Discrete

Continuous

Question 2

Describe ‘Normal distribution’

Answer 2

• Bell-shaped curve
• Most common distribution in nature
• Symmetrical

Question 3

Give an example of a pattern that shows normal distribution

Answer 3

Height of humans

Question 4

What are the two types of skewed distribution?

Answer 4

Negative and Positive

Question 5

Describe ‘Skewed Distribution’

Answer 5

• Can be negative or positive
• Mean is not the most common value
• Most common value is not central

Question 6

Give an example of skewed distribution

Answer 6

The age of deaths (skewed to 70-80 years)

Question 7

What should a representative sample have?

Answer 7

Same mean and degree of variation about the mean as the population as a whole

Question 8

What should be considered when assessing precision and accuracy?

Answer 8

• Mean of replicated measurements
• Variation in these replicated measurements
• Number of samples tested
• How regularly measurement equipment requires calibration

Question 9

What is a confidence interval?

Answer 9

Statistical estimate of range of values within a certain percentage of the total population would be found

Question 10

What is a statistically significant result?

Answer 10

One in which the difference between groups is unlikely to be due to chance alone

Question 11

What p value shows the results are statistically significant?

Answer 11

0.05

Question 12

What are the two types of control groups?

Answer 12

Negative and Positive

Question 13

What does a negative control group do?

Answer 13

Provide data for what happens in the absence of a treatment

Question 14

What controls should be used to test for false positive results?

Answer 14

Negative

Question 15

What do positive control groups prove?

Answer 15

The experimental design can detect a change in the dependent variable when one occurs

Question 16

What gives an indication of the strength of the correlation?

Answer 16

Dispersion of the points about the line

Question 17

In what circumstances can correlation demonstrate causation?

Answer 17

When all the confounding variables are controlled

Question 18

Where are in vitro studies carried out?

Answer 18

Lab

Question 19

Describe ‘In Vivo’ Studies

Answer 19

‘Within the living’

Studies involving living organisms

Question 20

Give two advantages and disadvantages of in vivo studies

Answer 20

Advantages:
- Provides data for effects in whole organisms
- Allows study of complex interactions
Disadvantages:
- Expensive and time consuming
- Difficult to prove causation

Question 21

Give two advantages of in vitro studies

Answer 21

• Simpler and less expensive
• Easier to control confounding variables
• Interpretation of results is simpler

Question 22

Give two disadvantages of in vitro studies

Answer 22

• Difficult to extrapolate results to whole organisms

- Difficult to model complex interactions