3. experimentation

Question 1

what is validity?

Answer 1

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

Question 2

what is reliability?

Answer 2

consistent values in replicates (repeated or independent)

Question 3

what is accuracy?

Answer 3

data/mean sets of data are close to the true value

Question 4

what is precision?

Answer 4

measured values are close to each other

Question 5

what is a pilot study used to do?

Answer 5

help plan procedures, assess validity and check techniques

Question 6

what do pilot studies allow for?

Answer 6

evaluation and modification of experimental design
the investigator to establish the number of repeat measurements required to give a representative value for each datum point

Question 7

what can the use of a pilot study ensure?

Answer 7

an appropriate range of values for the independent variable

Question 8

what can independent and dependent variables be?

Answer 8

continuous or discrete

Question 9

what do simple designs involve?

Answer 9

one independent variable

Question 10

what do multifactorial designs involve?

Answer 10

more than one independent variable

Question 11

what are observational studies able to detect?

Answer 11

correlation

Question 12

what are observational studies unable to detect and why?

Answer 12

causation, as they do not directly test a hypothesis

Question 13

what are confounding variables?

Answer 13

variables that may affect the dependant variable other than the independent variable being investigated

Question 14

how should confounding variables be handled?

Answer 14

held constant, or monitored so that their effect on the results can be accounted for in the analysis

Question 15

what is an advantage of lab work?

Answer 15

it allows simpler experiments to be conducted more easily as lab conditions can be controlled

Question 16

what is an advantage of field work?

Answer 16

the findings can be applied to a wider setting

Question 17

what is a disadvantage of lab work?

Answer 17

organisms may alter their behaviour when removed from their natural habitat

Question 18

what is a disadvantage of fieldwork?

Answer 18

it may not be as accurate of an observation

Question 19

what is an observational study?

Answer 19

a study in which the independent variable is not directly controlled by the investigator for ethical or logistical reasons

Question 20

how do randomised block designs work?

Answer 20

blocks of treatment and control
groups are distributed in such a way that
the influence of any confounding variable is
likely to be the same across the treatment
and control groups

Question 21

what do controls allow?

Answer 21

scientists to make comparisons with the results of treatment groups

Question 22

what is a negative control?

Answer 22

gives results in the absence of treatment

Question 23

what is a positive control?

Answer 23

treatment applied to check that a positive result can be detected

Question 24

what are placebos?

Answer 24

a substance that is included in the treatment without the independent variable being investigated

Question 25

what is the placebo effect?

Answer 25

where a measurable change occurs in the dependent variable which is due to patient expectation rather than the independent variable

Question 26

what does in vitro mean?

Answer 26

performing a given procedure in a controlled environment outside of a living organism

Question 27

what are examples of in vitro studies?

Answer 27

cells growing in a culture medium, proteins in a solution, purifying organelles

Question 28

what are the advantages of in vitro studies?

Answer 28

- large scale production - easy to culture - less ethical issues

Question 29

what are the disadvantages of in vitro studies?

Answer 29

- expensive - possible contamination

Question 30

what does in vivo mean?

Answer 30

experimentations using a whole living organism

Question 31

what are the advantages of in vivo studies?

Answer 31

- results will be more accurate - findings could be inferential

Question 32

what are the disadvantages of in vivo studies?

Answer 32

- causes harm to living things - time consuming

Question 33

when will researchers measure a representative sample of a population?

Answer 33

when it is impractical to measure and record every individual

Question 34

how is an appropriate sample size determined for a population?

Answer 34

depending upon the degree of natural variation - the greater the variation, the greater the sample size

Question 35

what is a representative sample?

Answer 35

a sample that shares the same mean as the population as a whole, and the same variation about the mean

Question 36

what happens in random sampling?

Answer 36

members of the population have an equal chance of being selected

Question 37

what is an example of random sampling?

Answer 37

a quadrat

Question 38

what is good and bad about random sampling?

Answer 38

G - reduces bias B - can give poor representation

Question 39

what happens in stratified sampling?

Answer 39

the population is divided into categories that are then sampled proportionally

Question 40

what is stratified sampling ideal for?

Answer 40

areas where there are different types of ground cover

Question 41

what happens in systematic sampling?

Answer 41

members of a population are selected at regular intervals

Question 42

what is an example of systematic sampling?

Answer 42

use of a line transect

Question 43

what may be the reason for variation within a set of experimental results?

Answer 43

the reliability of measurement methods/inherent variation in specimens

Question 44

what can carrying out repeated measurements within the instrument allow for?

Answer 44

ensured precision but not necessarily accuracy

Question 45

how can natural variation in a population be determined?

Answer 45

by measuring a sample of the population

Question 46

what does the mean of the repeated experiments give a suggestion of?

Answer 46

the true value

Question 47

why should independent replication be carried out?

Answer 47

to produce independent data sets

Question 48

what does having independent replicates allow for?

Answer 48

comparison and determination of reliable results (if results are consistent)

Question 49

what is qualitative data?

Answer 49

subjective and discriptive

Question 50

what is quantitive data?

Answer 50

measured objectively and assigned a numerical value

Question 51

what is ranked data?

Answer 51

where a numerical set is sorted from highest to lowest and assigned a rank

Question 52

when does correlation occur?

Answer 52

when there is a relationship between two variables

Question 53

when does causation occur?

Answer 53

if the change in the values of the independent variable are known to cause changes in the dependent variable

Question 54

does correlation imply causation?

Answer 54

no not necessarily

Question 55

when does positive correlation exist?

Answer 55

increase in one variable accompanied by increase in the other

Question 56

what does negative correlation exist?

Answer 56

increase in one variable accompanied by decrease in the other

Question 57

what shows the strength of correlation?

Answer 57

the spread of values form the line of best fit