Unit 3 - Investigative Biology Flashcards
What is a discrete variable?
Can have a finite range of values.
What is a continuous variable?
Can have an infinite, uncountable range of values.
What is accuracy?
Data is close to the true value.
What is reliability?
Consistent values are achieved in repeats and independent replicates.
What is validity?
Variables are controlled so that any measured effect is likely to be due to the independent variable.
What is precision?
Measured values are close to each other.
What 3 ethical considerations must be adhered to in human studies?
Informed consent
The right to withdraw
Confidentiality
What 3 ethical considerations must be adhered to in animal studies?
Replacement - animals are replaced with alternatives such as tissue cultures or less sentient species.
Reduction - minimal number of animals are used to achieve robust results.
Refinement - using methods that minimise potential pain, suffering or distress on the animals.
What process ensures that published data is scientifically correct?
Peer review.
What 4 things must be published in scientific reports so that others are able to repeat an experiment?
Methods, data, analysis, conclusions.
What is a null hypothesis?
Statement which proposes that there will be no statistically significant effect as a result of the experimental treatment.
What is the process of the scientific cycle?
Observation Hypothesis Experimental design Gathering, recording and analysis of data Evaluation of results Conclusion If necessary, revise the hypothesis
What is it called when a biological investigation fails to find an effect?
Negative result.
What is a pilot study?
Small-scale, preliminary study used to plan procedures, assess validity and check techniques.
What are the advantages of carrying out a pilot study?
- plan procedures, assess validity and check techniques
- allows evaluation/modification of experimental design
- ensure appropriate range of values for independent variable
- establish number of repeats required for representative values
What is a negative control?
Provides results in the absence of treatments.
What is a positive control?
Ensures that the system can detect a positive result when it occurs.
What is a placebo?
Treatment without the presence of the independent variable being investigated.
What is the placebo effect?
Measurable change in the dependent variable as a result of the patient’s expectations rather than a change in the independent variable.
What is random sampling?
Members of a population have an equal chance of being selected.
What is systematic sampling?
Members of a population are selected at regular intervals.
What is stratified sampling?
The population is divided into categories that are then sampled proportionally.
What is qualitative data?
Data which is subjective and descriptive.
What is quantitative data?
Data which can be measured objectively, usually with a numerical value.
What is ranked data?
Data transformation in which numerical values are replaced by their rank when data is sorted from highest to lowest.
What is a correlation?
Relationship between two values where they both follow the same pattern.
What can be used when confounding variables cannot easily be controlled?
Randomised block design.
What is a confounding variable?
Variable, other than the independent or dependent variables, which may affect the results so must be considered during the investigation.
What is an experiment with more than one independent variable called?
Multifactorial.
What is a dependent variable?
Variable that is measured.
What is an independent variable?
Variable that is controlled.
What is in vivo experimentation?
Experimentation using a whole, living organism.
What is in vitro experimentation?
Experimentation in a controlled environment outside of a living organism. (eg test tubes)
What is an advantage and a disadvantage of in vitro experiments?
Advantage - Better control of experiment and any confounding variables
Disadvantage - Not possible for many biological studies
What is an advantage and a disadvantage of in vivo experiments?
Advantage - Get a better idea of what is going on inside the cell or organism
Disadvantage - Living organisms show great variability which cannot really be controlled.
What is a representative sample?
Sample which shares the same mean and degree of variation around the mean as the population as a whole.
What is the median?
Middle value for the data.
What is the mode?
Most common value for the data.
What indicates high variability on a graph?
Large error bars.
What is a statistically significant result?
Result that is unlikely to be due to chance alone.
State the 6 ways in which data can be processed for analysis.
Graph, mean, median, mode, standard deviation and range.
What indicates that results are statistically significant?
Their error bars do not overlap.
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.
When may the validity of an experiment be compromised?
When confounding factors influence the value of the dependent variable.
What 3 things should scientific reports contain?
Explanatory title,
Abstract including aims and findings,
Introduction explaining the purpose and context of the study including the use of several sources, supporting statements, citations and references.
