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Title: 1st: Key Skills in Biological Sciences
Description: 1st year Key Skills in Biological Sciences notes, University of Exeter
Description: 1st year Key Skills in Biological Sciences notes, University of Exeter
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3: LIBRARY RESEARCH
1
5&6: STATISTICS
2
7: ACADEMIC MISCONDUCT AND PLAGIARISM
7
8: POSTER TIPS
7
9: USING EXCEL
8
10: CRITICAL READING AND WRITING
8
11: REFERENCING
11
12&14: DESIGNING AN INVESTIGATION
13
13&16: PRESENTING DATA
14
15: TIME MANAGEMENT
17
17: REVISION AND EXAMS
17
Joanna Griffith (2017)
3: LIBRARY RESEARCH
Extra information (outside lectures) is needed for:
○ Background reading around a research topic
○ Comparisons with primary research from articles in scientific journals
● Hierarchy of resources:
○ Original articles (containing primary research)
○ Literature reviews (secondary research)
○ Books
○ Organisational websites (for government and scientific organisations)
○ blogs/Wikipedia/other non-official websites
The Penryn library
● Loans:
○ Self-issue and return 24/7
○ Allowance of 20 items and 2 DVDs
○ Loan period of 6 weeks, unless books are High Demand or Reference copies
● Finding books for biosciences:
○ Biodiversity = 333
...
00
○ Genetics = 576
...
80
○ Ecology = 577
...
00
○ Animal behaviour = 591
...
00
○ Birds = 598
...
00
● Catalogue = lib
...
ac
...
names/numbers)
○ Ordinal
■ Orders observations along a continuum (eg
...
concentration, weight, height)
Central tendency
● Measures the spread of data
● If you take repeated samples from a population and calculate their averages they will
be normally distributed (Central Limit Theorem)
● Central tendency can be described using mean, median, and mode
○ Don’t use all of them at once, think about the characteristics of the data
● Mean
○ Where do most of the observations lie?
○ Always an estimation of the population mean, and is referred to as the sample
mean
○ Sample mean = sum of each observation/number of observations in the
sample
○ Problems:
●
Joanna Griffith (2017)
■
■
○
Skewed data strongly distorts the mean
Does not work as well as other central tendency techniques if
exceptional values in the data distort clustering, or if data has a trend
(scatter plots), or is bimodal
Rules:
■ The mean of a set of observations:
● Does not indicate that any of the observations have that exact
value
● Some of the values in the dataset may not even be close to the
mean value
■ Means can be used safely when observations cluster around a central
value (central tendency)
● Median
○ Middle observation in a dataset where values have been ranked in terms of
magnitude
○ Rank data in increasing order, and find the middle value
■ If there are even numbers of observations in the set, use the mean of
the two middle observations
○ Rules:
■ ‘Resistant statistic’ that is less susceptible to outliers or extreme
values, unlike mean
● Better for use with skewed datasets
■ More affected by changes in values near the middle of the distribution
■ Not easily written as an equation
■ Hard to use with large datasets
● Mode
○ The value in any set of observations which occurs most frequently
○ Rules:
■ Can indicate a “normal” or “usual” figure
■ Use when numbers in a distribution are not evenly distributed around
a central value
■ Is a value that actually occurs (unlike median, which can be a decimal)
■ Not useful if there is no single most frequently occurring value
Descriptive statistics
● Visualise the spread/distribution of data values
○ Eg
...
between different species
Skewness and kurtosis
● Skewness: degree of displacement in the peak
○ The closer the peak is to the middle, the less skewed it is
● Kurtosis: ‘peakedness’ (degree to which data values are concentrated at one point)
Summary of descriptive statistics
● Descriptive statistics are used to condense data into a single meaningful value
(mean, median, and mode) and illustrate central tendency
○ Don’t use all of them at once, consider distribution of data, skewness, and
kurtosis
Joanna Griffith (2017)
Standard deviations are the building blocks of probability testing and confidence in
the dataset
○ Don’t use all of them at once, consider distribution of data, skewness, and
kurtosis
● Standard deviations are the building blocks of probability testing and confidence in
the dataset
Statistical tests for significance
● Parametric tests
○ Make strict assumptions about the data being analysed
○ Requires data to be normally distributed
○ Requires around 50+ observations
● Non-parametric tests
○ Not based upon stringent assumptions of normality
■ Therefore slightly weaker
○ Can be run on small data sets (<20)
● Statistical tests for level 1 (accessed through Excel)
○ To use Excel to find the difference between data on two samples, you must
have:
■ Two measured variables or two counts of things
■ More than 15 observations per sample
■ An equal number of observations for each variable
○ Tests for a difference
■ Student’s t-test
● Sample against population
■ Difference of means t-test
● Two individual samples
■ T-test for tied samples
● Measures of the same set of organisms at two time points
○ Tests for a relationship (correlation)
■ Are the two variables being tested related in some way?
● Often, there is not a perfect relationship because other
variables may have had an effect on the dependent variable
● The variability around the line of each point determines the
strength of the correlation
● Normality
○ A bell curve for a single sample
○ A straight line for trends/correlations
● Variance
○ Before using a statistical test, check that the data sets look different and
conform to the requirements of normality
○ Variance = standard deviation2
○ In order to check that the data adheres to the assumption of equal variance,
an F-test, Kolmogorov or Shapiro test can be used
● Significance
●
Joanna Griffith (2017)
The means of two samples may look different from each other, but the
distributions of the measurements which were used to calculate the means
might overlap or intersect
○ The P value
■ Used to demonstrate the confidence we have that out data sets are
different from one another or correlated
■ If the value is 0
...
05, n = …’
○ Correlation:
■ ‘There was a significant correlation between x and y, that was strongly
positively correlated (P-value = <0
...
05 does not mean there was no underlying effect,
just that none was detected
● Extrapolating beyond the data is risky (patterns found within a data range will not
necessarily be true outside of it)
● Data can be cherry-picked, but selecting data in a huge dataset that looks like it has
a pattern doesn’t prove anything
● Pseudoreplication
● Randomisation (eg
...
by referencing
badly)
Detection
● Turnitin has a plagiarism checker
○ Checks for similarities with websites and other submitted work
○ Can detect when whole passages have been copied with words changed
○ Technical names cannot be written any other way, so will be picked up, but
markers understand
Avoiding plagiarism
● Write down details needed for referencing
● Use Harvard (Exeter) or Vancouver to reference
● Instead of copying a text, read a page and summarise it in your own words
● If you’re using an exact piece of text, use quotation marks
○ Cite author’s name and date of publication, and reference at the end of the
document
● Paraphrase
● Cite AND reference
○ It is not necessary to do this for common knowledge
--------------------------------------------------------------------------------------------------------------------------●
8: POSTER TIPS
Posters are still a major form of communication in science
○ Peer review publications
○ Scientific conference presentation
○ Scientific conference posters
Content
● Title
○ Should be visible from a few metres away
○ simple/clear
○ Eye catching but not distracting
○ Name, institution, and contact details underneath
● introduction/background
○ Set the scene
○ State why the question being investigated is important
○ Refer to (and reference) a few relevant studies
○ Bullet points are easier to read
● Methods
○ Simple, not necessarily detailed enough to be replicable
○ Give key information such as date/time
○ Details of how data was collected and prepared
○ Details of how bias was reduced
● Results
○ Don’t show raw data
○ SLAPU graphs
○ Talk about key trends (don’t interpret!)
●
Joanna Griffith (2017)
●
discussions/conclusions
○ Summarise and interpret main points
○ Compare to other published work (reference)
○ Suggest possible future work (evaluation)
■ Discuss the limitations of your own work, but don’t obsess over them
● References
○ Harvard or Vancouver
○ 3 or 4 minimum
Making the poster
● Data collection
○ Use Excel to collect data and produce graphs
● Draft writing
● Tends to look better landscape
● Consider symmetry in layout
● Consider use of colour
● Consider use of fonts
○ San serif easier to read when enlarged
--------------------------------------------------------------------------------------------------------------------------9: USING EXCEL
--------------------------------------------------------------------------------------------------------------------------10: CRITICAL READING AND WRITING
●
●
●
●
Non-critical: addresses text at face value
Critical: addresses text as one portrayal of fact
○ Looks beyond what a text says to consider how it portrays the subject matter
How to be critical:
○ Gather complete information
○ Understand and define all terms
○ Question the methods by which facts are derived
○ Question the conclusions
○ Look for hidden assumptions and biases
○ Question the source of facts
○ Don’t expect all of the answers
○ Examine the big picture
○ Examine multiple cause and effect
○ Watch for thought-stoppers
○ Understand your own biases and values
The world is full of misleading information
○ News is exaggerated to provide a good story
○ Advertisements
○ Even academics and researchers may bend the truth, eg
...
title in italics
...
place of publication: publisher
● Chapters in books
○ Chapter author(s), publication date
...
book editor(s)
...
place of publication: publisher, page numbers
● Journal articles
○ Article authors, publication date
...
journal title in italics, volume
number (issue number), page numbers
● Internet documents
○ Document author(s), date
...
place of publication:
publisher
...
) or exploratory (already have a hypothesis in mind, making
observations prior to testing it)
Hypothesis
● A clear statement articulating a plausible explanation for observations
○ What you think is happening, based on your knowledge of theory and biology
● H1: alternative hypothesis
○ The behaviour that we are seeing is biologically interesting
● H0: null hypothesis
○ Can be statistically tested
○ ‘Nothing is going on’/conservative
● For every hypothesis that suggests something interesting is happening, there must
be a corresponding null hypothesis that states that nothing is happening
○ By testing the null hypothesis, you gain information about the alternate
hypothesis
Predictions
● What we expect to happen if our hypothesis is correct
○ Good predictions follow on logically from hypotheses and will lead to obvious
studies that allow the prediction to be tested
■ If your H1 was correct, what would you expect your results to look like?
● Predictions about differences
○ Involve a difference between two or more groups
● Predictions about trends
○ The relationship between two continuously distributed measures
Testing a prediction
● What are you going to measure?
● How are you going to measure it?
● How many replicates do you need?
○ Replication: repetition of an experimental condition so that the variability
associated with the phenomenon can be estimated
● What variables may confound your results?
○ Assumption: a causes b or b causes a
■ In reality, c, a confounding variable, may cause a or b
●
Joanna Griffith (2017)
How will you sample your population?
○ Random
○ Systematic
○ stratified
Introduction
● Why the study was undertaken
○ State hypothesis and predictions
■ What does another person need to know about how you arrived at
these?
○ Background to the study
■ Any theoretical or previous experimental/observational work that led to
the hypothesis you are testing
■ Likely to include:
● References to previously published work
● Sometimes, a critical review of competing ideas
● A clear statement of the hypotheses and predictions to be
tested
--------------------------------------------------------------------------------------------------------------------------●
13&16: PRESENTING DATA
●
●
●
The importance of displaying data
○ Communicating information
■ Display frequencies
■ Illustrate associations between variables
■ Show differences between groups
○ Aids data analysis
■ Visualise patterns or reveal general trends
■ Important step in undertaking data analysis and applying statistical
techniques
○ Graphing should initially be explorative
■ Get a feeling for what graph would best suit the data
Guiding principles for presenting data
○ Clear, unambiguous representation of data
○ Have a point - illustrate trends and comparisons
○ Keep it simple
○ If it isn’t useful, get rid of it
Rules:
○ Appropriately descriptive axes titles, with units
○ Correct scale
○ No title, use figure number instead
■ No ‘a graph to show…’, just state what the graph is
○ Big and clear
○ Use a key/legend if appropriate
○ The x-axis is always the independent variable, the y-axis is always the
dependent variable
Joanna Griffith (2017)
○ Don’t join the dots unless the x-axis is time
○ Choose a suitable graph style
Display types
● Bar charts
○ Used to display a variable for a set of categories
■ X-axis = grouping (categorical) variable
■ Y-axis = quantitative variable
○ Y-axis scale should include 0 to put the bar heights into context
○ Using Excel
■ Remove gridlines and graph borders
■ Remove legend (if unnecessary) and chart title
■ Reformat axes
■ Edit x and y axis labels and add axis titles
■ Modify colour as required
● Histograms
○ Uses height or area to display the frequency distribution of a single numerical
variable
■ X-axis = continuous quantitative variable, broken into discrete classes
called ‘bins’
■ Y-axis = frequency of each ‘variable class’ in the dataset
○ Columns are continuous/adjacent
○ Excel is not great for generating histograms
● Box plots
○ Uses boxes and whiskers to display data distributions, usually media, IQR
and data range
■ X-axis = category/grouping
■ Y-axis = numerical variable
○ Concise method for displaying data distributions
○ Excel doesn’t have a function for producing box plots
● Line graphs
○ Uses dots connected by lines to display trends in a variable over time or any
other ordered series
○ Used when a categorical variable on the y-axis can be ordered or is
quantitative
○ X-axis is usually time, and a trend is mapped over increasing time
● Scatter plots
○ Used to present relationships between two variables
■ Each point on the graph represents a pair of observations (an x and a
y value, like coordinates)
■ X-axis = independent variable (driving the effect/unchangeable)
■ Y-axis = dependent variable (affected by the independent variable)
○ Can include a regression line (regression or smoothing function fitted to the
observations)
○ How do two variables behave relative to one another = correlation
○ Does variable 1 predict variable 2 = regression
● Pie charts
Joanna Griffith (2017)
○
Displays proportion/sizes of categories (a slice is proportional to the value of a
category)
Rare in science, doesn’t show much more than a table
○
Tables
○ Simple method for displaying frequencies or data summaries
■ Summary, contingency, frequency
Standard deviation/error
● Any time an ‘average’ is plotted, a measure of the variation associated with the
estimate must be stated
● Standard deviation is good, standard error is usually better (whichever is smallest is
best)
○ Standard error is a version of standard deviation, scaled to the amount of data
● Error bars
○ Gives a measure of how well a sample represents the population
■ When the sample is representative, standard error is small
■ Generally, if the error bars for your data do not overlap, you have
shown that there is a statistically significant difference
■ Symmetrical, on either side of the mean (above and below the plotted
point)
Interpreting data
● Results
○ ONLY what was found
○ Graph shows these trends…
○ No interpretation
● Discussion
○ What do your results mean?
○ accept/reject hypothesis and null hypothesis
○ Explain findings one by one
■ Do findings support and/or refute similar and/or related studies in the
field
○ Mention methodological limitations, but stay positive
○ Forecast next steps for research in the field
--------------------------------------------------------------------------------------------------------------------------●
15: TIME MANAGEMENT
Know what you have to do
● Make a complete to-do list
Prioritise tasks
● Sort tasks into:
○ Urgent and important
○ Urgent and not important
○ Not urgent and important
○ Not urgent and not important
Timetable time
● We all have the same amount of available time
Joanna Griffith (2017)
○ 2,016 hours in a 12-week term
● Create a timetable
○ Remember the fun stuff too
○ When do you work best?
● Break up large tasks into smaller chunks
Setting smart deadlines
● Specific
● Measurable
● Achievable
● Realistic
● timed
--------------------------------------------------------------------------------------------------------------------------17: REVISION AND EXAMS
● Past exam papers: lib
...
ac
...
5 hours before)
○ Avoid unnecessary distractions
○
Joanna Griffith (2017)
○ Stay relaxed but focuses
● The exam
○ Check the number of questions
○ Check both sides of the paper
○ Plan or make notes before answering if necessary
○ Keep an eye on the time
○ Allow time to check answers
○ If you don’t know how to answer a question, come back to it
Dealing with stress
● Practice deep breathing
● Stay positive
● Remind yourself of your past successes (but don’t get cocky)
Joanna Griffith (2017)
Title: 1st: Key Skills in Biological Sciences
Description: 1st year Key Skills in Biological Sciences notes, University of Exeter
Description: 1st year Key Skills in Biological Sciences notes, University of Exeter