General Field Skills

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  • Created by: exam yes
  • Created on: 16-05-19 20:09
What is the difference between Correlation and Regression?
Correlation indicates a link between two variables but does not explain or suggest CAUSATION, regression implies a cause and effect and so the variables involved actually directly affect eachother...
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What is 'r' related to Correlation?
The Pearsons correlation coefficient which only associated with linear correlation graphs.
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What can be deduced from an 'r' coefficient ?
The value lies between -1 and 1. The closest it is to 0, the more random the data and so the less correlated. If it is minus or positive = its a negative or positive correlation...
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If the correlation coefficient was 1, what would be deduced from the datas correlation?
There is a strong positive correlation and all values are along the straight line on a graph
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How are regression variables presented on a graph?
The cause is the independent variable and so is the x axis. The effect (what you measure) is on the y axis
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How does the Observed Value in an experiment relate to the 'True Value'?
The true value is always unknown and so the observed value/mean is the best estimate of the true value
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What is the error?AND how does this relate to Standard Uncertainty?
The Observed - True value. and So uncertainty is the best estimate of the error ( s.d / square root of n)
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What happens to experimental factors e.g. error if the Sample size is increased?
The error/Uncertainty decreases and accuracy increases and so the observed value that is measured is more likely to be closer to the true value...
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What is falsifiability?
Proving a statement, theory or hypothesis is wrong..
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Give 5 examples of potential physical conditions of an area...
pH, dissolved oxygen or carbon dioxide levels, shelter availability, temperature and water content (of soil for example)...
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What are 'Discrete' observations?
There is a number scale but not all values are possible ..
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What is Phase 1, 2 and 3 of a vegetation survey? (brief)
Phase 1 = general description of habitat type. Phase 2 = applying a specific habitat zone. Phase 3 = doing intensive surveys and sampling... (MORE)
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What is the difference between systematic and stratified random sampling?
Both involve mapping areas with grid systems. But systematic is more structured where the same place in each 'square' of the grid is sampled...stratified however, is when each 'square' is randomly sampled within the grid
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What sampling method is better for measuring species abundance of animals?
Density measurements
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What is a disadvantage of using Percentage cover to measure species abundance of plants in a field?
May not always inlcude species that exist in lower layers or that are hidden by other plants and so underestimates the actual cover...
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Describe nested quadrats...
A series of different sized quadrats which all have a common corner point.. with the smaller ones included within the area of the progressively larger ones
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How do you work out the minimum number of quadrats you will need for a sampling experiment ?
Do a practise experiment and then plot cumulative mean against the number of samples taken... If the mean stops increasing on the graph then sample number at that point is how many you use
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Why are limpets larger upper shore than lower shore?
The upper shored limpets need to retain more water and be secured to the rock for longer due to them being exposed for longer compared to the lower shored ones having longer water coverage
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When looking at two data sets, what 5 things would you include in a comparison ?
The Sample Size- which is larger i.e. better. The Error/Uncertainty- which is smaller i.e. more accurate. The Mean- general comparison. The Standard Deviation- which is smaller i.e. less varied + more precise The P-values- conclude the results...
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If looking at a histogram and data, what 5 things would you include when describing the results?
Sample size- is it good enogh
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If looking at a histogram and data, what 5 things would you include when describing the results?
Sample size- is it good enough. Normality- is the data normal? Histogram- does the graph show evidence of non-normality i.e. is it skewed? Skew+Kurtosis- what do these tests actually show? P-Value- conclude the results...
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What is Representative Sampling?AND why?
Sampling a small part of an area or population of a species which accurately represents the whole area or all individuals.. Done usually to save money, time and effort on difficult sampling jobs e.g. very large area
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What is the difference between flow rate and discharge rate?
Flow rate is the speed of the water flow whereas discharge rate is the volume of water that is transported through a given cross sectional area (determined using flow rate).
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What is the unit of flow/discharge rate?
E.g. cubic metres per second
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What is the definition of a P-Value?
Represents the probability of the alternative hypothesis being true or the null hypothesis being rejected
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What does homoscedasticity mean?
Having the same scatter of results e.g. on a graph... and so the variance is relatively equal (so same distance away from line of best fit)??
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Other cards in this set

Card 2

Front

What is 'r' related to Correlation?

Back

The Pearsons correlation coefficient which only associated with linear correlation graphs.

Card 3

Front

What can be deduced from an 'r' coefficient ?

Back

Preview of the front of card 3

Card 4

Front

If the correlation coefficient was 1, what would be deduced from the datas correlation?

Back

Preview of the front of card 4

Card 5

Front

How are regression variables presented on a graph?

Back

Preview of the front of card 5
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