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2.5 Data presentation and interpretation

2.5 Data presentation and interpretation

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Question 132

An ecologist is studying the impact of soil salinity, sss (measured in mS/cm), on the maximum growth height, hhh (measured in cm), of a particular marsh grass. Data collected from 10 different sites are plotted on a scatter diagram. For 9 of these sites, the data points exhibit a strong negative linear correlation. However, the 10th site, labeled 'Site Omega', is located at (48,82)(48, 82)(48,82), which is positioned significantly above the trend line observed in the other 9 sites.

Scatter diagram of maximum growth height against soil salinity, showing nine negatively correlated sites with a trend line and Site Omega at (48, 82) well above the line.

a.

State why Site Omega might be considered an outlier in this context.

[1]
b.

For the other 9 sites, the following summary statistics were calculated:

Sss=648.2,Shh=392.5,Ssh=−415.8 S_{ss} = 648.2, \quad S_{hh} = 392.5, \quad S_{sh} = -415.8 Sss​=648.2,Shh​=392.5,Ssh​=−415.8

Calculate the product moment correlation coefficient, rrr, for these 9 sites. Give your answer to 3 significant figures.

[2]
c.

If Site Omega were included in the calculation of the product moment correlation coefficient for all 10 sites, state what effect this would have on the value of rrr.

[1]
Markscheme

2.5 Data presentation and interpretation Questions

  1. A Level
  2. /Maths
  3. /2.5 Data presentation and interpretation

278 exam-style questions on CCEA A Level Maths 2.5 Data presentation and interpretation, covering 2.5.1 Data presentation and interpretation, 2.5.2 Data presentation and interpretation, 2.5.3 Data presentation and interpretation, 2.5.4 Data presentation and interpretation, 2.5.5 Data presentation and interpretation, 2.5.6 Data presentation and interpretation, 2.5.7 Data presentation and interpretation, 2.5.8 Data presentation and interpretation, 2.5.9 Data presentation and interpretation, and 2.5 Data presentation and interpretation. Each one has a worked solution and a mark scheme showing where the marks go.

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