Unit 3 Flashcards
What is Science?
Science is the gathering and organization of testable and reproducible knowledge.
In Science what is the norm?
Refinement of ideas.
What can scientific knowledge be thought of as?
Current best explanation.
What can scientific knowledge’s best explanation be updated after?
Evaluation of further experimental evidence.
State the stages in the Scientific Cycle.
- Observation
- Constructing a testable hypothesis
- Experimental design
- Gathering, recording, and analysis of data from the experiment.
- Evaluation of results and conclusion
What may the Scientific Cycle lead to?
The new or refined hypothesis meaning the cycle continues.
What does the Null Hypothesis of an experiment propose?
That there will be no statistically significant effect as a result of the experimental treatment.
Up until when is the Null Hypothesis generally assumed true?
Until evidence proves otherwise.
What can the Null Hypothesis be used to do?
Design an experiment to investigate a possible effect.
When is the Null Hypothesis rejected?
If there is evidence for an effect unlikely due to chance.
State the Null Hypothesis for both of these experiments.
1) If you measure the surface area of the feet of a male and female chicken.
2) If you feed chocolate to chickens and look at the results of the sex ratio.
1) The average surface area in the male chicken feet is the same as the average surface area in the female chicken.
2) There is no effect of feeding chocolate to chickens on the resulting sex ratio
All data should be gathered and recorded accurately in what?
Data Tables
In Data tables you should be consistent in what and what?
decimal places and units
How can data be analysed?
Calculations or by presenting it in Graphical form
What does data analysed in graphical form allow people to see?
See any trends in Variables.
Why is a statistical analysis carried out?
to see trends in variables and prove the result is not due to chance.
When is the failure to find a long term (negative result) effect a valid finding?
As long as an experiment is designed.
How can conflicting data or conclusions be resolved?
Through careful evaluation
What can conflicting data or conclusions lead to?
further more creative experimentation
Knowledge of NEGATIVE RESULTS is Important because?
Prevent needless duplication of results
Present a more realistic representation of the “messy” nature of scientific research
Can lead to a realisation of flaws in well-established science
Can inspire others to alter the experiment and gain positive results
When do scientific ideas become accepted?
once they have been independently checked
How are ‘one of results’ treated with?
Caution
Why is it essential to take independent repeats of the experiments?
As one of results treated with caution.
Describe how repetition should be carried out?
At a different time with a completely new set of chemicals and equipment
What does scientific literature and communication allow?
Findings to be shared with others to further research
What should scientific communication include?
Method
Data
Analysis
Conclusion
Why should scientific communication include Method
, Data, Analysis & Conclusion?
allows other to repeat the experiment
Name some common methods of sharing original scientific findings.
Seminar (a presentation followed by questions and discussion, usually within a team or with researchers in the same field)
Talks (a presentation to a wider audience)
Posters at conferences (an illustrated summary of research)
Publishing in academic journals
What does the end product of science tend to be?
The publication of scientific journal articles
Most of the scientific population use what type of review?
PEER
What is peer review?
Peer review is a process where:
Peer review is a quality control process allowing readers of peer-reviewed journals to make assumptions about the quality of the science.
specialists with expertise in the relevant field assess the scientific quality of a submitted manuscript.
specialists make recommendations regarding the suitability of the article for publication.
Why is the peer-review process is slow to accept radical new ideas?
since the peer reviewers tend to be those who are already established in that field.
What is ‘mental inertia’?
the peer-review process is slow to accept radical new ideas since the peer reviewers tend to be those who are already established in that field.
This is known as mental inertia and it can take many years for new ideas to become established as fact.
Why are review articles useful?
Review articles are a really useful tool to gain a broader understanding of a particular area because they summarise current knowledge and recent findings in a particular field.
There is increasing interest in science and a corresponding increase in scientific coverage in the wider media. What in the media is common?
The misrepresentation of science
How do we combat the misrepresentation of science in the media?
By trying to increase the population’s scientific evaluation skills
While judgements and interpretations of scientific evidence may be disputed, What are of key importance in science.
integrity and honesty
How can honesty and integrity be maintained in science?
By reporting unbiased presentation of results, citing and providing references and avoiding plagiarism.
What reduces the opportunity for dishonesty or the deliberate misuse of science?
The replication of experiments by others
What is plagerism?
Passing off another person’s writing or ideas as your own is plagiarism.
To distinguish between original work and ideas that have already been published, what are scientists required to do?
Cite and supply references.
Replication of experiments by others reduces the opportunity for what?
Dishonesty.
The publication of original findings requires the publication of what?
Full methods
What is operational replication
Other scientists can then repeat the same experiment. This is known as operational replication – the exact repetition of an experiment by another scientist.
Replication reduces the chances of deliberate misuse of what?
science.
Animals are often used in biological studies, when using animals scientists have a duty to do what?
Scientists have a duty to ensure animal suffering is kept to a minimum.
What are the 3 R’s when dealing with animals in experiments?
Replacement – the use of animals should be replaced with alternatives as often as possible.
Reduction – the number of animals used in a study should be reduced as much as possible.
Refinement – for those animals being used, the negative impact on them should be minimised.
The 3 R’s are used to do?
avoid, reduce or minimize the harm to animals.
Clinical trials often use humans. What should be considered when using humans in experiments?
Informed consent – participants should be given details of the study and the opportunity to decline to take part.
Right to withdraw – participants should have the option to withdraw their consent to participate right up until publication of the data.
Confidentiality – any data gathered should be anonymous in order to protect the rights of participants.
Any scientific research on living organisms should be what?
justified
any risks in completing the research should be assessed. This includes taking into account the risk to and safety of what?
subject species, individuals , investigators and the environment.
What is the definition of legislation?
laws governing various aspects of science. Legislation limits the potential for the misuse of studies and data.
What can influence Scientific research?
Legislation, regulation, policy and funding
The value or quality of science investigations must be justifiable in terms of what?
the benefits of its outcome, including the pursuit of scientific knowledge.
As a result of the risks involved, many areas of scientific research are highly what?
regulated and licensed by governments.
Define Validity?
Validity - Variables controlled so that any measured effect is likely to be due to the independent variable.
Define reliability?
Reliability – consistent values in repeats and independent replicates.
Define Accuracy?
Accuracy – data, or means of data sets, are close to the true value.
Describe Precision?
Precision – measured values are close to each other.
What is a pilot study used to help plan?
Integral to the development of any investigation, a pilot study is used to help plan procedures, assess validity and check techniques.
What do pilot studies allow (in terms of experimental design
This allows the evaluation and modification of experimental design.
The use of a pilot study can insure and allows investigators to do what?
The use of a pilot study can ensure an appropriate range of values for the independent variable.
In addition, it allows the investigator to establish the number of repeat measurements required to give representative values
Advantages of Pilot studies.
Allows new protocol to be developed
Appropriate range values for the independent variable
Always practice established protocol
Avoid results from the dependent variable going “off the scale”
Checks whether results can be produced in a suitable time frame
Allows the number of repeat measurements to be estimated
Allows identification of compounding variables which need to controlled
What is the independent variable?
The independent variable is the variable that is changed in a scientific experiment.
What is the dependent variable?
The dependent variable is the variable being measured in a scientific experiment.
By varying the independent variable and monitoring its effect on the dependent variable we seek to prove or disprove what?
Hypothesis
The effect of a dependent variable can be continuous. What does continuous mean?
Anywhere in a range of values
The effect of a dependent variable can be discrete. What does discrete mean?
Falls into 2 or more distinct categories
Experiments involve the manipulation of the independent variable by the investigator.
True or False
True
The experiment treatment group is compared to what other type of group
Control
What is a simple experiment?
A simple experiment is one where only one independent variable is investigated e.g. measuring the effect of temperature on enzyme activity
Advantage of a simple experiment.
An advantage is that it is easy to control conditions of the laboratory and so allows the experiment to be conducted more easily than in the field.
A disadvantage of a simple experiment
A drawback of a simple experiment is that its findings may not be applicable to a wider setting.
What is a multifactorial study?
A multifactorial experiment involves a combination of more than one independent variable or combinations of treatments.
Investigators may use groups that already exist, so there is no what?
Truly independent variable
What are observational studies?
In observational studies, the independent variable is not directly controlled by the investigator, for ethical or logistical reasons.
Instead of the independent variable being controlled in a multifactorial experiment they use what?
Instead they use pre-existing groups to investigate correlation between variables
Advantage of multifactorial experiment
They are good at detecting correlation
Disadvantage of multifactorial experiment
but since they do not directly test a hypothesis, they are less useful for determining causation.
Due to the complexities of biological systems, other variables besides the independent variable may affect the dependent variable.
Such variables are called what?.
confounding variables
What is a confounding variable?
A confounding variable is any factor which affects the dependent variable that is not the independent variable.
These confounding variables must be held constant if possible, or at least monitored so that their effect on the results can be what?
can be accounted for in the analysis.
In cases where confounding variables cannot easily be controlled, what could be used.
a randomised block design
What is 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 a control group?
A control group is set up in an experiment to prove that it is the independent variable which is the cause of any effect seen in results.
What are the control results used for?
comparisons with results of treatment groups
What is negative Control?
Negative controls provide results in the absence of treatment.
What is an example of negative control?
A good example is the addition of denatured enzyme to substrate when studying the effect of that enzyme on the substrate.
What is a positive control?
A positive control is a treatment that is included to check that the system can detect a positive result when it occurs.
What is a positive control group?
A positive control group is a control group that is not exposed to the experimental treatment but that is exposed to some other treatment that is known to produce the expected effect.
Placebos can be included as a treatment without the presence of what being investigated?
independent variable
What is the placebo effect?
Placebo effect is a measurable change in the dependent variable as a result of a patient’s expectations, rather than changes in the independent variable.
What is a in vitro experiment?
In vitro refers to the technique of performing a given procedure in a controlled environment outside of a living organism.
Examples of in vitro experiment?
Examples:
Cells growing in culture medium
Proteins in solution
Purified organelles
What is in vivo experimentation
In vivo refers to experimentation using a whole, living organism.
Advantages of in vitro
Less expensive
Less time-consuming
Disadvantages of in vitro
Less precise
Incomplete representation of the in vivo system
Advantage of in vivo
More precise
Accurately represent the in vivo situation
The disadvantage of in vitro
Expensive
More time-consuming
Where it is impractical to measure every individual what is used to sample
a representative sample of the population is selected.
What determines the sample size?
The extent of the natural variation within a population determines the appropriate sample size.
More variable populations require what (in terms of sample size)
a larger sample size.
Less variable populations require what (in terms of sample size)
a smaller sample size.
A representative sample should contain what?
Should share the same mean and the same degree of variation about the mean as the population as a whole
What is random sampling?
In random sampling all members of the population have an equal chance of being selected.
Random sampling reduces the possibility of what?
bias
The disadvantage of Random sampling
However, it can result in poor representation of the overall population.
Advantages of random sampling
straight-forward process.
What is systematic sampling?
In systematic sampling, members of a population are selected at regular intervals. E.g. line transect.
Advantages of systematic sampling
This provides a more representative sample of the whole population.
A disadvantage of systematic sampling
however, the sample may be biased because all members do not have an equal chance of being selected.
What is stratified sampling?
The population is organised into groups or ‘strata’ according to a characteristic e.g. age.
The number of individuals sampled is in proportion to the groups size in the main population.
Advantage of stratified sampling
This type of sampling is highly representative of the overall population.
The disadvantage of stratified sampling
However, setting up this technique requires the researcher to know the proportions of each group prior to beginning. This may not always be possible.
Variation in experimental results may be due to what?
the reliability of measurement methods and/or inherent variation in the specimens.
The reliability of measuring instruments or procedures can be determined by what?
Repeated measurements
readings of an individual datum point.
The variation observed indicates the precision of the measurement instrument or procedure but not necessarily what?
Its accuracy.
What are some natural variations in biological material?
Human Heart Rate
Daphnia (water flea) Heart rate
The natural variation in the biological material being used can be determined by WHAT?
measuring a sample of individuals from the population.
The mean of these repeated measurements will give an indication of the true value for the organism being measured.
The range of values is a measure of the extent of variation in the results.
If there is a narrow range then the variation is what?
LOW
Independent replication should be carried out to produce WHAT?
independent data sets.
These independent data sets should be compared to determine what?
reliability of the results.
When can Overall results be considered reliable
if they can be achieved consistently.
Discrete and continuous variables give rise to what?
qualitative, quantitative or ranked data.
What are discrete variables?
a limited number of possible types of characteristics
What are continuous variables?
a range of values
The type of variable being investigated has consequences for what?
any graphical display or statistical tests that may be used.
What is quantitative data?
Quantitative data is data which can be measured objectively, usually with a numerical value, e.g. time, volume, height. Quantitative data is easy to plot in graphical form and can be analysed statistically.
Examples:
(Discrete independent variable)- Investigating the effect of gender on reaction time
(Continuous independent variable)- Investigating the effect of pH on enzyme activity
What is qualitative data?
Qualitative data is subjective and descriptive . The data cannot necessarily be measured and it is difficult to analyse statistically.
E.g. colour change (yes or no), male or female, patient symptoms
Examples:
(Discrete independent variable)- Investigating patient symptoms using three different treatments
(Continuous independent variable)- Investigating the effect of incubation temperature on sex of offspring
What is ranked data?
Ranked data refers to the data transformation in which numerical values are replaced by their rank when the data are sorted from lowest to highest.
E.g. observing social animals and assigning dominance rank
Placing data into a sequence, e.g. time taken to complete a task
What is the mean?
Mean – average value (sum of numbers divided by the number of measurements).
What is the median?
Median – middle value when the data is placed in sequence
What is the mode?
Mode – most frequent value in data set.
What can boxplots be used to show?
Box plots can be used to show variation within and between data sets.
What should a boxplot include?
Box plots should include:
Median
Lower quartile
Upper quartile
Inter-quartile range.
Error bars can be added to graphs to indicate what?
the variability of data around the mean.
Error bars can show what? (2 things!)
They can show a direct measure of variation (using standard deviation)
Or probabilities (using confidence intervals).
The smaller the error bars, how variable the data?
The smaller the error bars, the less variable the data.
What is a confidence interval?
A confidence interval is a statistical estimate of the range of values within which a certain percentage of the total population would be found.
A 95% confidence interval shows that the range of values would include 95% of the whole population being studied.
When does correlation exist?
when graphing data correlation exists if there is a relationship between two variables.
What is a positive correlation?
A positive correlation exists when an increase in one variable is accompanied by an increase in the other variable.
What is a negative correlation?
A negative correlation exists when an increase in one variable is accompanied by a decrease in the other variable.
When values align closely to the line of best fit the correlation if described as being what?
strong
When the values do not align closely to the line of best fit the correlation is described as being what?
weak
Strength of correlation is proportional to what?
the spread of values from the line of best fit.
Correlation is an association and does not imply what?
Causation
Causation can only be shown when what?
all confounding values are adequately controlled and so is difficult to demonstrate in observational studies.
Causation exists when what?
if the changes in the values of the independent variable are known to cause changes to the value of the dependent variable.
What can a scientific report contain?
Scientific reports should contain:
An explanatory title
An abstract (aim and findings)
Introduction explaining the purpose and context of the study (including use of several sources, supporting statements, citations and references)
Describe the title?
Should provide a succinct explanation of the investigation
Independent- caffeine
Dependent- cardiac output
Organism being studied e.g mice
Describe the abstract?
The abstract (or summary) outlines the aims and findings of the study Which variable was altered and how?
Which variable was measured and how?
What was the effect of altering the independent variable on the dependent variable?
The introduction should provide any information required to support what?
Choices of method
Results
Discussion
What should the introduction explain?
why the study has been carried out and place the study in the context of existing understanding.
Key points should be summarised and supporting and what type of information identified.
contradictory information
Describe what needs to be included in the introduction
The introduction should provide any information required to support:
Choices of method
Results
Discussion
An introduction should explain why the study has been carried out and place the study in the context of existing understanding.
Key points should be summarised and supporting and contradictory information identified.
Several sources should be selected to support statements, and citations and references should be in a standard form e.g. Harvard or Vancouver.
Decisions regarding basic selection of study methods and organisms should be covered, as should the aims and hypotheses.
Background information should be clear, relevant and unambiguous.
What should the aim involve
linking independent and dependent variable
What should the method section contain?
A method section should contain sufficient information to allow another investigator to repeat the work.
Experimental design should address what?
the intended aim and test the hypothesis.
An experimental design is valid and will allow valid conclusions to be made if?
the independent variable can be systematically altered
the dependent variable can be measured
Any confounding variables should be taken into account or standardized across treatments.
treatment effects are compared to appropriate controls.
The validity and reliability of the experimental design should be what?
evaluated.
When is an experimental design invalid
When it does not address the intended aim or test the hypothesis
When is the validity of an experiment compromised?
The validity of an experiment may be compromised when factors other than the independent variable influence the value of the dependent variable.
Name some common confounding variable
Volume of Enzyme Concentration of enzyme Volume of Substrate Concentration of substrate PH of solution Temperature of solution
What is selection bias?
Selection bias is the selection of a sample in a non-random way, so that the sample is not representative of the whole population.
Selection bias is the selection of a sample in a non-random way, so that the sample is not representative of the whole population.
True or False
True
What is Puesdo Replication?
Taking multiple measurements without changing equipment
What is true replication?
Repeating the whole investigation again using a new set of equipment.
The replicate should similarly incorporate repeated measurements and have a large sample size.
Results must then be analysed, this could involve in calculation and presentation of what?
Consideration should be given to the validity of outliers and anomalous results.
The mean,
Median
Mode
Graphs
Standard deviation
Range of data
How should data be presented?
Data should be presented in a clear, logical manner suitable for analysis.
Consideration should be what in results?
The validity of outliers and anomalous results.
Statistical tests are used to determine what?
whether the differences between the means are likely or unlikely to have occurred by chance.
The variability of results can be presented as what?
can be presented as a number or displayed on a graph of the data as an error bar.
A statistically significant result is what?
one that is unlikely to be due to chance alone.
What happens when the difference is found to be statistically significant?- what is rejected
If the difference is found to be statistically significant then the null hypothesis can be rejected.
Providing the experiment has been designed to effectively control the confounding variables then what can be concluded?
That the single factor by which the data sets differ is likely to be causing the difference between the results.
What do error bars indicate?
Error bars indicate the variability of data around a mean.
If the treatment mean differs from the control mean sufficiently for their error bars not to overlap this indicates what?
this indicates that the difference may be significant.
What should conclusions refer to?
Conclusions should refer to the aim, the hypothesis (stating if it should be rejected or not) and be supported by the data.
The validity and reliability of the experimental design should be taken into account.
Consideration should be given as to whether the results can be attributed to correlation or causation.
Evaluation of conclusions should also refer to existing knowledge and what?
the results of other investigations this will allow meaningful scientific discussion.
Scientific writing should reveal an awareness of what?
The contribution of scientific research to increasing scientific knowledge, and to the social, economic and industrial life of the community. Do your findings have a potential impact in society, living organisms or the environment?
Describe critical analysis of results?
Critical analysis of results is essential part of any conclusion. This is where you take your statistical evidence to state the conclusion is valid because SD’s are small, p-values are small or there is little variation between repeat experiments.
You should discuss big differences between control and experiment groups (if there is one), making reference to the error bars or confidence intervals.
