3.Experimentation

Question 1

What is accuracy?

Answer 1

data, or means of data, are close to the true value.

Question 2

What is precise?

Answer 2

measured values are close to each other.

Question 3

What is validity?

Answer 3

variables controlled so that any measured effect is likely to be due to the independent variable.

Question 4

What is reliability?

Answer 4

Consistent values in repeats and independent replicates.

Question 5

what is a pilot study used to?

Answer 5

• Help plan procedures
• Assess validity
• Check techniques

Question 6

What does a pilot study allow?

Answer 6

Allows evaluation and and modification of experimental design.

Question 7

What does the pilot study allow?

Answer 7

Allows appropriate range of values for the
independent variable and the investigator to establish the number of repeat measurements required to give a representative value for each independent datum point. - Suitable number of replicates.

Question 8

What are independent vairables?

Answer 8

The variable that is changed in a scientific experiment.

Question 9

What are dependent variables?

Answer 9

The variables being measured in a scientific experiment.

Question 10

What are discrete variables and what method would be used to plot data?

Answer 10

Are distinct and unrelated to each other. Results are displayed by bar graph.

Question 11

What are continuous variables and what method would be used to plot data?

Answer 11

Have a range of values. Results are displayed using a line graph.

Question 12

Why are controls used?

Answer 12

As a comparison with treatment groups - Controls show that any effects are the result of the treatment.

Question 13

What is the purpose of a negative control?

Answer 13

Provides results in the absence of a treatment.

Question 14

What is the purpose of a positive control?

Answer 14

To check if the system can detect a positive result when it occurs.

Question 15

What is a placebo?

Answer 15

One group receives a tablet with the drug and the other group receives a tablet without the drug.

Question 16

What is the placebo effect?

Answer 16

A measurable change in the dependent variable as a result of a patients expectations rather than a change in the independent variable.

Question 17

What do in vitro investigation consist of?

Answer 17

An investigation carried out in a controlled environment outside of living organisms.

Question 18

What are examples of in vitro experiments?

Answer 18

• Cells growing in a culture medium
• Proteins in solution
• Purified organelles

Question 19

What do in vivo investigations consist of?

Answer 19

An investigation carried out using a whole organism (in a living orgainsm)

Question 20

What do in vivo investigations consist of?

Answer 20

An investigation carried out using a whole organism (in a living organism)

Question 21

What are the advantages of in vitro experiments?

Answer 21

Confounding variables may be easily controlled.

Question 22

What are the disadvantages of in vitro experiments?

Answer 22

Its relevance may be limited in in vitro results may not transfer to in vivo.

Question 23

What are the advantages of in vivo experiments.

Answer 23

Allows researchers to investigate the overall effect of an agent on a living organism.

Question 24

What are the disadvantages of in vivo experiments?

Answer 24

Many confounding variables difficult to control.
Fieldwork experiments are more applicable to a wider biological setting but there is a lack of control experimental variables.

Question 25

What should be done if sampling every individual is impractical?

Answer 25

A representative sample of the population is selected.

Question 26

What determines the appropriate sample size?

Answer 26

The extent of the natural variation within a population.
More variable populations require a larger population size.

Question 27

What should a representative sample have?

Answer 27

The same mean and the same degree of variation about the mean as the populations as a whole. (Thus preventing selection bias).

Question 28

What is random sampling?

Answer 28

Random sampling is when members of the population have an equal chance of being selected.
This could be done by pick numbers out of a hat or computer generation.

Question 29

What is systematic sampling?

Answer 29

Members of a populations are sampled at regular intervals. e.g. line transect.

Question 30

What is stratified sampling?

Answer 30

The population is divided into categories that are the sampled proportionally.

Question 31

What may be the reason for variation in experimental results?

Answer 31

• Reliability of measurement methods
• Inherent variation in the specimens

Question 32

What is precision?

Answer 32

The closeness of repeated measure to each other.

Question 33

What is accuracy?

Answer 33

The closeness of the measured value to the true value.

Question 34

How can reliability of measuring instruments or procedures be determined?

Answer 34

Repeated measurements or readings of an individual datum point.

Question 35

What does variation observed from an investigation indicate?

Answer 35

The precision of the measurement instrument or procedure but not necessarily its accuracy.

Question 36

What is natural variation?

Answer 36

The natural variation in the biological material being used can be determined by measuring a sample from a population.

Question 37

What does the range of values measure?

Answer 37

The extent of variation in the results.
If there is a narrow range then the variation is low.

Question 38

Why should independent replication take place in a pilot study?

Answer 38

To produce independent data sets.