Unit 3.2 - Experimentation

Question 1

Define “valid” results

Answer 1

If confounding variables have been controlled so any measured effect is due to the independent variable

Question 2

Define “reliable” results

Answer 2

If the values generated between repeats are consistent

Question 3

Define “accurate” results

Answer 3

If the data is close to the true value

Question 4

Define “precise” results

Answer 4

When the measured values are close together

Question 5

What is a pilot study?

Answer 5

A small scale investigation of the planned research project

Question 6

What are three benefits of a pilot study?

Answer 6

Helps to plan procedures
Allows evaluation of experimental design
Ensures an appropriate range of values for the independent variable

Question 7

What is the type of experiment where there is more than one independent variable called?

Answer 7

Multifactorial

Question 8

Name advantages and disadvantages of multifactorial experiments?

Answer 8

Advantage - may be applied to a wider setting

Disadvantage - harder to clearly see findings

Question 9

Name the type of experiment with one independent variable?

Answer 9

Simple

Question 10

What does an observational study do and what are advantages and disadvantages?

Answer 10

They use groups that already exist (no true independent variable).
Advantage- detecting correlation
Disadvantage - determining causation

Question 11

What is a confounding variable?

Answer 11

Any factor which effects the dependant that is not the independent variable

Question 12

What is a positive control?

Answer 12

A treatment that is included to check that the system can produce a positive result

Question 13

What is a negative control?

Answer 13

Removing a key part of the experiment to check to see if results are provided in the absence of treatment.

Question 14

What is a placebo used for?

Answer 14

To test the patients expectations

Question 15

Describe and give one example of “in vitro”?

Answer 15

Performing an experiment in a controlled environment outside of a living organism. Example: cells in a culture medium

Question 16

What is “in vivo”?

Answer 16

Experiments carried out using a whole living organism

Question 17

Give advantages and disadvantages of “in vitro”

Answer 17

Advantage - simple and inexpensive

Disadvantage - difficult to apply results to whole organisms

Question 18

Give advantages and disadvantages of “in vivo”

Answer 18

Advantage - provides data for whole organisms

Disadvantage - results difficult to interprate

Question 19

What are features of a representative sample?

Answer 19

The same mean and degree of variation as the whole population

Question 20

Describe random sampling

Answer 20

Members have an equal chance of being selected. Reduces bias

Question 21

Describe systematic sampling

Answer 21

Members are selected at regular intervals. More representative than random but may be biased

Question 22

Describe stratified sampling

Answer 22

Population divided into categories that are sampled proportionally. Highly representative however properties within the population must be known