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