Things I forget 2.0 Flashcards
What are the 3 Rs in animal studies?
- replacement
- reduction
- refinement
Define the 3 Rs in animal studies?
- Replacement
- methods which avoid or replace the use of animals
- reduction
- fewer animals being used
- refinement
- minimise pain and distress and increase animal welfare
How must scientific research be justified and risk assessed?
- value of scientific investigations must be justifiable in terms of the benefits of its outcome, including the pursuit of scientific knowledge
- as a result of risks involved, many areas of scientific research are highly regulated and licensed by governments
What must be taken into account when conducting scientific research?
the risk to and safety of:
- subject species
- individuals
- investigators
- the environment
What other factors can influence scientific research?
legislation
regulation
policy
funding
What is the effect of legislation on scientific research?
it limits the potential for the misuse of studies and data
What is the definition of validity?
variables controlled so that any measured effect is likely to be due to the independent variable
What is the definition of reliability?
consistent values in repeats and independent replicates
What is the definition of accuracy?
data, or means of data sets, are close to the true value
What is the definition of precision?
measured values are close to each other
What is a pilot study used for?
- it is integral to the development of an investigation
used to help: - plan procedures
- asses validity
- check techniques
What are the benefits of carrying out a pilot study?
- allows evaluation and modification of experimental design
- can ensure an appropriate range of values for the independent variable
- be able to establish the number of repeat measurements required to give a representative value for each independent datum point
Explain observational studies and correlation and causation
- good at detecting correlation, but since they do not directly test a hypothesis
- they are less useful for determining causation
Explain how to carry out a randomised block design
Randomised blocks of treatment and control groups can be distributed in such a way that the influence of any confounding variable is likely to be the same across the treatment and control groups.
What is the role of a negative control?
it provides results in the absence of a treatment
What is the role of a positive control?
a treatment that is included to check that the system can detect a positive result when it occurs
What is the placebo effect?
a measurable change in the dependent variable as a result of the patients expectations, rather then the changes in the independent variable
What is a placebo?
included as a treatment without the presence of the independent variable being investigated
When is a larger sample size required?
more variable populations
What should a representative sample have?
it should share the same mean and the same degree of variation about the mean as the population as a whole
What are the 3 types of sampling?
random
systematic
stratified
What is stratified sampling?
the population is divided into categories that are then sampled proportionately
What may variation in experimental results be caused by?
- reliability of measurement methods
- and / or inherent variation in the specimens
Why should independent replication be carried out?
to produce independent data sets
When can overall results only be considered reliable?
if they can be achieved constantly
What should happen to independent data sets and why?
- they should be compared
- to determine the reliability of results
What is qualitative data?
subjective and descriptive
What is quantitive data?
can be measured objectively. usually with a numerical value
What is ranked data?
the data transformation in which numerical values are replaced by their rank when the data are sorted from lowest to highest
How do you calculate median?
- order values from lowest to highest
- find the middle value
- if there are two middle values, then add them together and divide by two to find the middle value
How do you calculate mode?
- order numbers from either lowest to highest or highest to lowest
- count how many tines each number appears in the set
- the one that appears most is the mode
- there can be more than one mode, or no mode
How do you find the lower quartile, upper quartile and interquartile range
- find the median
- find the median of the first half of the data (Q1)
- find the median of the second half of the data (Q3)
- find the difference between Q3 and Q1 (Q3-Q1)
What are box plots used for?
to show variation within and between data sets
What is an error bar?
a line through a point on a graph, parallel to one of the axes, which represents the uncertainty or variation of the corresponding coordinate of the point
What is the difference between correlation and causation?
correlation is an association and does not imply causation
When does causation exist?
if the changes in the values of the independent variable are known to cause changes to the value of the dependent variable
When does a positive correlation exist?
an increase in one variable is accompanied by an increase in the other variable
When does a negative correlation exist?
when an increase in one variable is accompanies by a decrease in the other variable
Explain strong and weak correlations
strength of correlation is proportional to spread of values from line of best fit
What should a method section contain?
sufficient information to allow another investigator to repeat the work
What should the experimental design address and why?
the intended aim and the hypothesis
the validity and reliability of the experimental design should be evaluated
an experimental design that does not address the intended aim or hypothesis is invalid
When may the validity of an experiment be compromised?
when factors other than the independent variable influence the value of the dependent variable
What is selection bias?
the selection of a sample in a non-random way, so that the sample is not representative of the whole population
What may prevent a representative sample being selected?
selection bias
When may it be impossible to avoid selection bias?
sample size may not be sufficient to decide without bias whether the change to the independent variable has caused an effect in the dependent variable
How do you determine weather the differences between means are likely or unlikely to have occurred by chance?
statistical tests
What is a statistically significant result?
one that is unlikely to be due to chance alone
What do error bars indicate?
the variability of data around a mean
What indicates that the difference may have been significant?
if the treatment mean differs from the control mean sufficiently for their error bars not to overlap
What should conclusions refer to?
- the aim, the results and the hypothesis
- the validity and reliability of the experimental design should be taken into account
- consideration should be given as to weather the results can be attributed to correlation or causation
What should evaluation of conclusions refer to?
existing knowledge and the results of other investigations
