experimentation

Question 1

discrete variable

Answer 1

a discrete variable is a variable that takes on distinct, countable values.

Question 2

continuous variable

Answer 2

a continuous variable is a variable that takes on any value within an infinite range

Question 3

qualitative variable

Answer 3

a variable that isn’t numerical

Question 4

quantitative variable

Answer 4

any variables where the data represent amounts

Question 5

independent variable

Answer 5

the variable that is changed in an experiment

Question 6

in vivo

Answer 6

involves observations made in a living organism

Question 7

in vivo advantage

Answer 7

allows effect on the whole organism to be observed

Question 8

why include a placebo group

Answer 8

provides results in the absence of the treatment

Question 9

ethical issues of trials

Answer 9

• informed consent
• right to withdraw
• confidentiality

Question 10

positive control

Answer 10

a treatment that is included to check that the system can detect a positive result when it occurs

Question 11

negative control

Answer 11

provides the results in the absence of treatment

Question 12

test assay

Answer 12

An assay is a process of analysing a substance to determine its composition or quality.

Question 13

accuracy

Answer 13

data or means of data sets are close to the true value

Question 14

precision

Answer 14

measured values are close to each other

Question 15

randomised block design

Answer 15

controls for confounding variables

Question 16

null hypothesis

Answer 16

the null hypothesis proposes that there will be no statistically significant effect as a result of the experiment treatment

Question 17

ranked data

Answer 17

data that has been compared to the other pieces of data and given a “place” relative to these other pieces of data.

Question 18

simple experiment

Answer 18

an experiment with one independent variable

Question 19

multifactorial experiment

Answer 19

an experiment with more than one independent variable or treatment

Question 20

reliability

Answer 20

consistent values are achieved in repeats and independent replicates

Question 21

selection bias effect

Answer 21

sample is not representative

Question 22

observational study

Answer 22

cannot show causation

Question 23

advantage of in vitro

Answer 23

the environment is closely controlled

Question 24

correlation

Answer 24

correlation is any statistical relationship, between two random variables.

Question 25

representative sample

Answer 25

same mean/same degree of variation about the mean as the population as a whole

Question 26

how to improve precision of readings

Answer 26

• repeat measurement
• single datum point to check measured values are close to each other

Question 27

peer review process

Answer 27

critical evaluation by experts in the relevant field

Question 28

standard curve

Answer 28

allows the determination of an unknown

Question 29

centrifuge benefit

Answer 29

only soluble materials will be present in the supernatant

Question 30

confounding variable

Answer 30

Variables other than the independent and dependent variables that may affect the results of an investigation and therefore need to be considered during the investigation

Question 31

random sampling

Answer 31

Members of the population have an equal chance of being selected.

Question 32

systematic sampling

Answer 32

Members of the population are selected at regular intervals

Question 33

stratified sampling

Answer 33

The population is divided into categories that are then sampled proportionally