Aim:
How and why does vegetation change across a
psammosere at Llobregat delta, Barcelona?
Data Presentation Techniques
What techniques of
data presentation could we use?
What techniques of
data presentation could we use?
What techniques of
data presentation could we use?
What techniques of
data presentation could we use?
What techniques of
data presentation could we use?
What techniques of
data presentation could we use?
Practising Data Presentations
Task:
• Using the data
opposite,
complete a
scattergraph
Discuss dependent & independent axis / students complete on graph paper / Click to show example
Practising Data Presentations
Spearman’s Rank Correlation Co-efficient
Why (Justify)?:
• A correlation can easily be drawn as a scatter
graph, but the most precise way to compare
several pairs of data is to use a statistical test.
• SRCC establishes whether the correlation is
really (scientifically) significant or if it could have
been the result of chance alone.
• SRCC establishes whether the relationship is
positive or negative and within at least 95%
certainty that two variables are related.
Spearman’s Rank Correlation Co-efficient
Hypothesis:
• We might expect to find that tree girth increases with distance along
a psammosere as the coniferous woodland establishes itself as the
climax vegetation.
The hypothesis might be written like this:
• Tree girths increase with distance inland along a mature dune.
• The more objective scientific research method is always to assume
that no such girth-distance relationship exists and to express the
null hypothesis as:
‘There is no significant relationship between tree girths
distance inland along a mature dune’.
Spearman’s Rank Correlation Co-efficient
What can go wrong?:
Having decided upon the wording of the hypothesis, you should
consider whether there are any other factors that may influence the
study. Some factors that may influence tree girths and their
measurement may include:
• Inconsistency in the collection of data. E.g. Failing to record the girths
at a point which is 1.3 metres up the tree.
• Inaccuracy in measuring the distance between trees. E.g. Not always
ensuring the measuring tape is taught before recording the data.
• Cumulative sampling may distort the expected girth-distance gradient if
several trees cluster within a short area along the transect line followed
by a considerable gap before the next group of trees.
• The influence of human intervention and management within the
psammosere. Is the coniferous woodland a plagio-climax; planted in
order to protect the psammosere?
You should mention such factors in your answer.
Spearman’s
Rank
Correlation
Click to reveal
Spearman’s Rank Correlation Co-efficient
Other factors to consider:
• The result will always be between 1 and -1.
• Even if two variables correlate cannot prove
anything - only further research can actually
prove that one thing affects the other.
• Data reliability is related to the size of the
sample. The more data you collect, the more
reliable your result.
Question 1
Question 3
Question 5
Question 2
Question 4
Question 6
Starter lesson 4
With reference to one technique you chose to
present data in your enquiry, justify the
choice of this technique.
You have only………..
With reference to one technique you chose to
present data in your enquiry, justify the
choice of this technique.
With reference to one technique you chose to
present data in your enquiry, justify the
choice of this technique.
With reference to one technique you chose to
present data in your enquiry, justify the
choice of this technique.
What are other likely opening questions
at AS Level?
What are other likely opening questions
at A2 Level?
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SKILLS DAY-SAND DUNES-LESSON 3