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adv biology > 3. experimentation > Flashcards

3. experimentation Flashcards

1
Q

what is validity?

A

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

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2
Q

what is reliability?

A

consistent values in replicates (repeated or independent)

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3
Q

what is accuracy?

A

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

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4
Q

what is precision?

A

measured values are close to each other

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5
Q

what is a pilot study used to do?

A

help plan procedures, assess validity and check techniques

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6
Q

what do pilot studies allow for?

A

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

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7
Q

what can the use of a pilot study ensure?

A

an appropriate range of values for the independent variable

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8
Q

what can independent and dependent variables be?

A

continuous or discrete

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9
Q

what do simple designs involve?

A

one independent variable

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10
Q

what do multifactorial designs involve?

A

more than one independent variable

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11
Q

what are observational studies able to detect?

A

correlation

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12
Q

what are observational studies unable to detect and why?

A

causation, as they do not directly test a hypothesis

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13
Q

what are confounding variables?

A

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

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14
Q

how should confounding variables be handled?

A

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

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15
Q

what is an advantage of lab work?

A

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

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16
Q

what is an advantage of field work?

A

the findings can be applied to a wider setting

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17
Q

what is a disadvantage of lab work?

A

organisms may alter their behaviour when removed from their natural habitat

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18
Q

what is a disadvantage of fieldwork?

A

it may not be as accurate of an observation

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19
Q

what is an observational study?

A

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

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20
Q

how do randomised block designs work?

A

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

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21
Q

what do controls allow?

A

scientists to make comparisons with the results of treatment groups

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22
Q

what is a negative control?

A

gives results in the absence of treatment

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23
Q

what is a positive control?

A

treatment applied to check that a positive result can be detected

24
Q

what are placebos?

A

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

25
Q

what is the placebo effect?

A

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

26
Q

what does in vitro mean?

A

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

27
Q

what are examples of in vitro studies?

A

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

28
Q

what are the advantages of in vitro studies?

A
  • large scale production
  • easy to culture
  • less ethical issues
29
Q

what are the disadvantages of in vitro studies?

A
  • expensive
  • possible contamination
30
Q

what does in vivo mean?

A

experimentations using a whole living organism

31
Q

what are the advantages of in vivo studies?

A
  • results will be more accurate
  • findings could be inferential
32
Q

what are the disadvantages of in vivo studies?

A
  • causes harm to living things
  • time consuming
33
Q

when will researchers measure a representative sample of a population?

A

when it is impractical to measure and record every individual

34
Q

how is an appropriate sample size determined for a population?

A

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

35
Q

what is a representative sample?

A

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

36
Q

what happens in random sampling?

A

members of the population have an equal chance of being selected

37
Q

what is an example of random sampling?

A

a quadrat

38
Q

what is good and bad about random sampling?

A

G - reduces bias
B - can give poor representation

39
Q

what happens in stratified sampling?

A

the population is divided into categories that are then sampled proportionally

40
Q

what is stratified sampling ideal for?

A

areas where there are different types of ground cover

41
Q

what happens in systematic sampling?

A

members of a population are selected at regular intervals

42
Q

what is an example of systematic sampling?

A

use of a line transect

43
Q

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

A

the reliability of measurement methods/inherent variation in specimens

44
Q

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

A

ensured precision but not necessarily accuracy

45
Q

how can natural variation in a population be determined?

A

by measuring a sample of the population

46
Q

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

A

the true value

47
Q

why should independent replication be carried out?

A

to produce independent data sets

48
Q

what does having independent replicates allow for?

A

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

49
Q

what is qualitative data?

A

subjective and discriptive

50
Q

what is quantitive data?

A

measured objectively and assigned a numerical value

51
Q

what is ranked data?

A

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

52
Q

when does correlation occur?

A

when there is a relationship between two variables

53
Q

when does causation occur?

A

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

54
Q

does correlation imply causation?

A

no not necessarily

55
Q

when does positive correlation exist?

A

increase in one variable accompanied by increase in the other

56
Q

what does negative correlation exist?

A

increase in one variable accompanied by decrease in the other

57
Q

what shows the strength of correlation?

A

the spread of values form the line of best fit

adv biology (13 decks)

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