Coursework elementsCoursework elements

Section A questions1. Rivers

2. Hazards

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RequirementRequirement• Only planning and data collection will be

tested for Section A questions. This involves:1. Choosing a subject and location2. Identifying a hypothesis to test3. Deciding on the data required

(remember data is not just numbers - its pictures, annotated sketches, maps, surveys, results of questionnaires - in fact any information related to the investigation)

4. Choosing a data collection technique5. Risk assessment6. Data collection strategy – what will you do?7. Sampling method8. Piloting??9. Data gathering/recording10.Identify secondary data where applicable

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Tasks: Tasks: what do you need to know about?what do you need to know about?

•Rivers: Measuring channel features measurement Measuring water quality

•Coasts: Beach measurements, eg profiles and

sediments Surveying peoples’ views on the

management of pressured and/or retreating coastlines

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Sampling methods come near Sampling methods come near the end of the list but they are the end of the list but they are

generalgeneral•What is sampling?•A ‘short-cut' method for investigating a

whole population The sum total of all the things you are

trying to measure – e.g. ALL the bedload in a river from source to mouth]

•Data is gathered on a small part of the whole ‘parent population' or ‘sampling frame' and used to inform what the whole picture is like.

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Why sample? Why sample? • In reality there is simply not enough:

Time Energy Money Labour / man power Equipment

• Besides which, many ‘populations’ are infinite so measuring the whole lot is just not possible.

• On which of these could you do a census (measure the whole population) – The dissolved oxygen in the River Wye? The rainfall caught in a rain gauge over 7 days (or even a whole year of 365 days)?

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What make better samples?What make better samples?• Larger sample sizes are more accurate

representations of the whole.• Ways to do this included taking more

measurements in the same place, or choosing more locations.

• Take bedload for example (stones on river bottom) – you could collect 20 instead of 10 at each location, or you could go to 6 locations instead of 3 and do 10 at each

• Or you could not only measure angularity and longitudinal measurements but possibly weight as well!

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What make better samples?What make better samples?• But difference in validity between large and

excessively so, is not great!• Stones again: a sample of 10 stones at one site

would give you more valid results than say 5, but increasing the sample to 100 really would not give you much more information than 10.

• Making sure bias is kept to a minimum makes for better results – especially in survey questions

• But think about stones, you could lean over the bank and pick those (a) nearest to the bank and (b) that you could easily pick up with one hand – you are hanging onto a branch of a tree to steady yourself with the other one! That could be biased, as there may be quite a few larger ones you could not pick up and the ones in the middle may mostly bigger or smaller than those at the edge (We will come back to how to get around that in a minute)

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Ways to sample:Ways to sample:•Three main types of sampling strategy: •1. Random •2. Systematic •3. Stratified

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Random SamplingRandom Sampling• Using chance (or random numbers) to decide where.• E.g. Measure the length of the river and then get 3

random numbers within the range of length and that is where you go!

• In theory, the least biased (which is its main advantage), but look what happened when I did this for a 10km long of river, which included upper, middle and lower course features - 2.477, 1.556, 4.503 – not much of the lower course there! So one big problem with this, is that you can miss out on whole sections of your population – the same as you would if you used random sampling to find out environmental quality in towns [in that case you would grid the whole area, number

each and use random numbers to pick which to visit]• But then we could right up against health and

safety issues – who is to say these spots are safe to visit – could be half way down a waterfall!

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Systematic samplingSystematic sampling• Samples are chosen in a systematic, or regular

way. E.g. They are Evenly spaced along a line e.g. every 20 metres along

a transect line. At equal regular intervals in time, e.g. every half hour

or at set times of the day. Regularly ‘numbered', e.g. every 10th house or

person.• This easier to do than random sampling and also

you don’t get parts missed out as in lower course of my mythical river. Great for urban transect/ environmental quality – do use the term given a chance!

• Could also use it sampling the stones on the river bed – put heavy rope across river and pick up the stone the rope is touching say every 20cm or so

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But variations on stratified sampling But variations on stratified sampling are probably the most useful for are probably the most useful for

geographygeography • In its purest form, this method is used when the population is made up of sub-sets of known size. That way you can random or systematically sample within the subset.

• So we know for example that our river has 2 distinct areas, lower, middle and upper course – say of 2km, 6km and 4km each.

• So to do this properly, we would sample 1 from the upper, 3 from the middle and 2 from the lower – but then we would hit the H&S issues if we did this on a purely random basis, but you could imply you were using a simplified stratified method which takes account of health and safety issues.

• This is also a good method for sampling environmental quality

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But variations on stratified sampling But variations on stratified sampling are probably the most useful for are probably the most useful for

geographygeography • In terms of sampling for questionnaires this is often used by market researchers and would be good when seeking opinions about for example how disasters were handled – you might know (or could find out – secondary sources) the proportion of people of various ages in a population, and so pick a similar proportion from each age group.

• So say you intend to do 50 interviews• The population: 38% are 60+, 30% are 41 – 60, 24%

are 21- 40, 8% are 16-20 and the remainder are too young to be asked.

• How many 21 – 40 year olds would you ask?• But the MAIN advantage is for stratified sampling is

you get a representative sample of every subgroup.

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Rivers: Choosing locations and Rivers: Choosing locations and health and safetyhealth and safety

• This is a big part of planning for any fieldwork around rivers – use OS maps or google maps or memory map or the OS site ‘get a map’ to investigate the area you are thinking about carefully (this is called secondary data by the way).

• You need to be sure you can safely carry out whatever procedures you are doing –

• So for example if you need to go into the river, you need to be very sure that it is not too deep and that bottom is solid enough - use a place where for example a footpath actually crosses the river as this is likely to have a ford if it does not a footbridge

• Better not to depend on that however! Try to go for working off a footbridge.

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Choosing locations and health Choosing locations and health and safetyand safety

•You need to be in at least 2 of you to do any measuring at all – from the practical point of view – timing activities – 2 ends of a tape etc – but also never go somewhere on your own where you could slip and fall in!

•You needed to decide exactly where the sites are and leave notice of them with another person who you can contact.

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Rivers: Measuring channel Rivers: Measuring channel features measurementfeatures measurement

•What channel features can you measures?

•What hypothesis would you form for each one?

•How would measure these channel features?

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• What measurements are these guys taking?• In general, how would you expect these

measurements to change as you went down stream? [I admit it will not happen for every point]

• What else could you work out by combining these 2 sets of measurements?

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• What measurement does this picture illustrate?• What is not shown in the diagram that you must

have to complete the measurement?• Why are there 3 channels?• What calculation will they need to do to record the

information they need?• What would be the units of the final answer?

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• One group of students are using this chart – it’s a power’s chart by the way – what is it for?

• What other measuring instrument would they need and what would use it to measure?

• What results would they expect as they went down stream? Why?

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Questions you may be askedQuestions you may be asked• Describe how you plan an investigation of

bedload over the course of a river? [Note planning would include H&S considerations,

finding and selecting the sites, secondary data search etc]

• You are to carry out an investigation on the speed of flow of a river over its course. What is your hypothesis? Why? How would carry out the work? [This is NOT planning, so begin the second part with ‘

Having established a selection of (? How many) safe sites …..’ How is it measured? How do you make sure you have a representative value (average)?

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When it comes to measuring When it comes to measuring water quality …water quality …

• There are not a load of different methods but there are certain items that you need to know you need to measure and to appreciate what results will show good water quality and what is bad.

• There are 4 physical ones, which are fairly straight forward: Temperature – too warm and there is less DO pH – neutral is good (pH 7) – too acid (poo? Wee? Acid rain?)

– too alkaline (most likely some chemicals from manufacturing or farming getting into the water)

Dissolved oxygen ( high is good – plants doing well and animals can breath). Low = too warm or too still or too many germs

Turbidity (how clear is it?) High turbidity means you cannot see through it – low = clear to the bottom. Can be just churned up due to heavy rain for example or can indicate bacteria, algae concentrations

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When it comes to measuring When it comes to measuring water quality …water quality …

• But there other things you can measure to check water quality beyond the range of students but you need to know what they are and what they show: Nutrients ( like nitrogen in the water from

fertilizer) Toxic substances like heavy metals for industry Species survey – too much of some things and

you have poor water, like bacteria, but lots of plants and insects is good – clean enough them so OK for us.

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Questions you may be askedQuestions you may be asked•Explain how the quality of water may

be measured using fieldwork.

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Coasts: What will you measure?Coasts: What will you measure?• The length, height and

slope of the beach, the size, shape and distribution of the particles making up the beach.

• This will usually be carried out using one or more transects (the more the merrier.

• As safety is less of an issue, then systematic sampling will be best

What is that?

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Method:Method:

• To measure the angle of a slope between two points you need two or three people.

• Identify a slope unit between two breaks of slope. Measure this distance. • Person A stands at the bottom of the slope with the clinometer resting on top of

a ranging pole. • Person B holds a second ranging pole at the top of the slope. • Person A sights the clinometer at the top of the ranging pole held by B and

reads off the slope angle. • Angles going uphill are recorded as positive (+) angles and downhill as negative

(-) ones. Measuring the angle of a slope at regular intervals is more straightforward, but it tends to hide the small variations in slope which can be important on a beach.

• Measuring from break of slope to break of slope means that you have to estimate where the slope angles change. This means that you normally end up taking more slope readings, but the profile that you draw is more accurate.

This is a clinometer

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Measure pebble size and shape a Measure pebble size and shape a various points on the beachvarious points on the beach

• If there is a single large groyne or jetty, take pebble measurements and profile readings at frequent intervals on both sides of the groyne. If there is a series of groynes on a beach, take pebble masurements and profile readings on either side of each groyne and at distances in between. At each interval, take a vertical transect from the sea shore up to at least the high-tide mark. Use a tape measure or ranging poles to ensure that you keep to a straight line.

• At 2m intervals up the beach, place a quadrat on the surface, and use this to select 10 stones from the surface. Measure the shape and size of each stone.

• Use the same methods explained on slide 18 for rivers

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Final section – attitude questionnaireFinal section – attitude questionnaire • Whilst you are expected to talk about

unbiased clear closed questions from which you can collect data, it might be interesting to say that this type of questioning is usually more useful if you want to find out facts – how old are you? How many cars do you own? How often do you go to the supermarket?

• That what people feel is much more difficult to find out by this method – and that discussion groups can be much more informative, but recording the results of those is more open to be influenced by what the person chairing the discussion thought!

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Issues with closed questionsIssues with closed questions• Ensure they are not biased (put hobby horses firmly

in the stable)• Make sure there are enough options to cover most

answers – think about whether you need ‘other’ as well as ‘don’t know/have no opinion’ or whether these can be combined.

• Only have yes/no where it is really relevant.• May like to use graduated box answers for opinions

(1 totally disagree to 5 strongly agree).• But if later you use these scores to graph please

make sure you don’t get confused!• I hate cat lovers – 5• I love cats – 1• Catty attitudes total 6 – does not tell you much about

the person!! Could have been any other combination to get same score!!!

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Anything wrong here?Anything wrong here?

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What about this part?What about this part?

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Questions you may be askedQuestions you may be asked•How would you find out what people

think of the management of coastal retreat?

• Include the type of questions•How you would decide on your sample

– sampling method•Where would you go to collect them?•Mention H&S issues.

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HomeworkHomework• I have 2 questions for each of rivers

and coasts for you to have a go at!