Tuesday, 31 January 2012

Live Session for Poole

Dear All

Thursday is the exam, so on wednesday, please submit any questions you have to the ticker, they will not appear immediately, but will appear at about 7:30 when I start the live session. Hopefully, we can cover most topics, but if you need to ask a question, this is the way! You can even replay it later if you aren't around tomorrow evening, but then, where else could you possibly want to be? Any question allowed, as long as it connects to Poole, bear in mind, the answers to your question will appear as fast as I can type!

Friday, 27 January 2012

Dear Upper Sixth,

As promised, the third post for our Unit 4B exam next week, the lovely Nikki Lewis has clarified the stats tests for you, and given you some examples to work through.

Please download the sheet to have a go, and there is an explanation there for each for you, but as a brief summary:

Spearmans Rank:

Explanation: Used to prove a relationship between two variables, the result is a positive or negative correlation, and this works well when there are only two variables, and for tests where you believe they will be connected.
Result: The result should always be between 1 and -1, and the closer to either end of that scale, the stronger the correlation.
Exam Answer: Make sure you comment on both the strength of the correlation and the level of significance at which it has been accepted, and state which hypothesis has been accepted.
Possible Tests: Type of employment against type of housing, type of employment against another type of employment (Do different economic groups live in the same region?), Population density against type of employment (Do those in higher managerial and professional roles live in less densely packed surroundings).

Chi Squared:

Explanation: A test used to asses if there is a statistically significant difference in distribution of frequencies across an area. This can be used to compare anything that can be expressed as a frequency, such as number of people employed in a certain category, or number of cars in a region. The test will tell you if there is a difference, but not where the difference is, or how much of a difference there is, once you have a positive result, you need to go back to the raw data to search for the difference and then explain the reason behind it.
Result: The result is the sum of all the Chi Squared values, and needs to be greater than the significance value for the degrees of freedom in your test. This is calculated by the number of columns minus one, multiplied by the number of rows minus one. Then you have to go back to the data to find the reason for the difference.
Exam Answer: If a difference has been proved, you can say that according to the result of the Chi Squared test, the positive hypothesis can be accepted, and there is a statistically significant difference between the distribution of frequencies in the given area. You should then refer to the observed frequencies in your test, and explain where the difference is, and any reasonable explanation, or explain how you would conduct further research to find the reason for the difference.
Possible Tests: Traffic observations over area affected by the new road network (pedestrians, lorries and cars over several areas), types of housing over areas, types of employment over areas.

Mann Whitney U:

Explanation: This test will tell you only if there is a significant difference in two sets of data, any data can be used, and for this test you do not need to have the same number of samples in each set of data. This means it is ideal for before and after surveys, particularly with the bridge, as you can add several more survey points to the new road network when it is complete, and still use this test.
Result: This test takes the lowest value or the two rows Mann Whitney values, and the result has to be BELOW the significance level for the number of data sets. The significance values will either be given to you, or will appear as a table such as this:

Exam Answer: The Mann Whitney U value shows that there has been a significant change, this can be seen in the data for x,y,z, and as such the new bridge is clearly reducing the congestion in Poole.
Possible Tests: If the result is accepted, then you have proved there is a significant difference, you need to asses the raw data to see if there is an increase or decrease.
Possible Tests: Traffic, change in population make up or densities before and after the bridge and redevelopment.

Stats for Blog

If you want us to mark any, email us, or leave a comment and I will get back to you!


Thursday, 26 January 2012

Data on Maps

Dear All

As some revision for Unit 4B, here are a selection of different ways to represent data on maps! You should be able to comment on how to present data, and the benefits and disadvantages of using each method. Remember that you could be asked to demonstrate your chosen method in the exam, and that you have already been given the full data range for the different SOA's. Hence, it would be a very good idea to look at the groups of data (Population Density, Employment, Housing) and to assess how you would represent each on the map you have been given.

1. Chloropleths

Description:This is a type of map where different regions are coloured or shaded according to their value in a given data set. The range of categories should not be too high (preferably no more than 5/6) and the colour choice needs to be appropriate, often it is best to use a graduated colour change option, rather than several completely different colours, which make it hard to interpret

Method: Assess the range of data for your given statistic, common examples would be population density. Divide this range into 5 or 6 categories, and assign a colour to each. Locate the correct area on the map and colour in according the value for that region. Ensure that you include a scale, title and a key for the colours.

Benefits: This is a very clear way of showing geographical variations in values, looking at a chloropleth allows you to identify patterns easily, and see if there is a geographical factor that is affecting the value, in the example shown, there is a significantly higher percentage of people employed in higher managerial professions living in the coastal areas of poole. This is also a relatively rapid way to transfer data onto a map, that does not require further calculations, specialist kit or programmes, or significant knowledge of statistical tecnhiques.

Disadvantages: It only effectively represents one piece of data, it cannot be used to display more complex data that covers a range of variable such as different emplyment groups, or types of housing.

Best used for: A value with only one variable, such as population density, where you think there could be a geographical pattern.

2. Locational Bar Charts

Description: Bar charts drawn for several categories of information (in this case three) that are drawn directly onto the area in which the measurements were taken. The one below is for percentage of people living in Owner Occupied, Private rented or council rented accommodation in each area. The bar charts need a scale and a key.

Method: Convert all values to percentages, decide on an appropriate scale for the bar charts, the scale needs to show the variation within the categories, but not be so large as to obscure the map. Locate a suitable point within each region to draw the bar chart, and try to ensure that the entire bar chart can be located within the region.

Benefits: Allows for multiple pieces of data to be clearly represented on the map, the result is clear and easy to read, highly visual and not too complicated. The graph does not require any special equipment, and the only maths involved is to convert to percentages, which is essential for comparison.

Disadvantages: Can only be used for a few pieces of data, too many and it becomes hard to read. Deciding on a scale can be difficult if there is a considerable amount of variation across the regions, as some bars will be very small. It can be quite time consuming, as each region will need a different graph.

Best used for: Data with several variables, but can be used for any type of data that is converted to a percentage. In the case of this AIB, the percentage of people in each type of housing, or the percentage in each type of employment would be suitable.

3. Stacked Proportional Bar Charts

Description: A percentage representation of a set of data located on a map with colours assigned to each category. The bar chart scale needs to be chosen carefully, as it needs to not obscure too much of the region, and large enough for the percentages in each category to be seen. 

Method: Convert all values to percentages of the total, decide on a scale that will allow clear data representation, and not too large for the map. Draw on the bar chart, shade in the areas, making sure you measure from the top of the last upwards, not the base of the bar chart. 

Benefits: Clear, allows multiple data values to be displayed, shows a clear pattern if one is there, only requires a conversion to percentages. 

Disadvantages: Time consuming, can overshadow the regions and is often difficult to locate all the bar charts on the map, some often have to be drawn off to one side which makes interpretation more difficult. 

Best used for: Data sets with a large range of values that need to be displayed on the map. 

5. Locational Pie Charts

Description: Pie charts drawn on the graph in or around the region and coloured according to category. 

Method: Find a suitable scale for the pie charts, draw the circles onto an appropriate area of the graph, trying to contain the chart within the region, and then complete each chart in turn with the appropriate values. 

Benefits: Very visual, allows multiple categories of data to be represented. 

Disadvantages: The pie charts can end up being quite small, hence the categories can be difficult to read, and the pie charts will obscure the region they are meant to represent. It is a very time consuming graph to draw, as Pie charts do require protractors and compasses. 

Best used for: Larger maps, with a large amount of data needs to be represented, suitable for any type of data, whether in percentage or not. 

6. Proportional Area Representations (Ok, I made that one up)

Description: The areas are shaded to a proportion of the area they represent, this is a more imaginative way to represent data, and could be valid as long as you justify why you have chosen it and explain your method clearly, but it is not part of the syllabus.

Method: Convert values to percentages, find the central point of each region, and draw a pie chart only extending out to the edges of the region. Colour according to value.

Benefits: Very visual. marks for creativity.

Disadvantages: Quite time consuming, and you have to work out a way to find the central point, then the area of the region could distort the true representation of the value, as the shape of the region changes through 360 degrees. 

Best used for: Possibly best not used in the exam, unless you are asked to come up with an imaginative new way to represent data. 

The key to doing well on map questions, is that you need to pick the right method to display the data they ask for. Some methods are inappropriate for multiple values, some are too time consuming to use in an exam, and some are too confusing to read, make sure you think about it, spend this weekend planning how you would plot all the data you have, AND any you could gather from fieldwork (I am thinking of an isoline map of traffic congestion before and after the bridge opens - but I may have spent too much time reading about Poole!). 

Also, bear in mind that the exam is next week, and the long delayed christmas movie will bring up sharply back into the study of plate tectonics and hazard management. Please feel free to bring popcorn to your first triple after the exam. 


Unit 4B word Cloud.

Dear All

In an effort to be exciting and dynamic with our teaching of 4B, here is a word cloud visualising the most common terms used in the AIB booklet. It may be useful to consider which words appear most frequently!

Get Adobe Flash player


Monday, 23 January 2012

Last Minute Live Revision

Dear Lower Sixth!

Tonight there will be e revision session online, here starting at 7:30 incase you have any last minute questions for tomorrow. You do not need to create an account, just submit your question in the box at the bottom, and wait for me to type a reply! (if it is a long reply be prepared to wait a  couple of minutes).

This is a "Silly Question Amnesty" so please ask anything, even if you feel we have covered it before, and bear in mind I have control over publishing your posts, so whatever you submit will not appear immediately!

 See you all soon, you can submit questions from now on (18:46) but I am just grabbing some dinner first, so they will be answered later. Millie

Saturday, 21 January 2012

Apps for revision

Dear All, 

This year sees the introduction of a new learning tool in both Geography and Geology, we have made use of the fantastic StudyBlue.com to bring you some revision Apps (You can access them through the website as well) and they are compatible with both iPhone/Ipod and Android. 

Ask yourself the question, click the circle to reveal the answer:

The account is free, and you can login through Facebook to prevent you having to remember another password! Once you have your account, it is then straighforward to add yourself to my classes, and save the resources you want to your "backpack". Those that are saved, will then be accessible through your mobile when you download the App. 

In order to find my classes: 

  1. When you create your account, the site will ask you where you study, type in "Richard Huish College"
  2. Search for "Millie"
  3. Select "Geography Geog AS"
  4. Go back to "my Backpack" (top center left of the page)
  5. In the class, on the right had side there is a news pane, this will show who else is in your class, and when any new resources are added. You should be able to find the resources in here, click on them in turn, and on the right hand side, select "Save to backpack/ Geography Geog AS" this will make them accessible on your phone.

Currently in the StudyBlue.com Geography class, there are apps for population and rivers terminology, and one for skills, with pictures of all types of graphs and stats tests you could be asked on tuesday, the case studies have pictures, and you can use them as flashcards to test yourself, or each other, and on the website, the flashcards can be turned into self marking tests. The site tracks your progress for each set of cards, and produces a score per session. You can then filter the cards out, and just revise the ones you didnt get the first time if you upgrade to studyblue+, but the site offers fantastic functions for free!

You then need to download the App (StudyBlue) from the relevant App store, or follow the links at the bottom of the page. The App is free, and once you log in you should find the flashcards there waiting for you. Any problems let me know, but you can then start revising.

There are several ways to work, and you do not need a smartphone, either on your phone or computer, check yourself for each card, and if you got it right, give it a thumbs up, if not, select thumbs down, and revise it again later on. When you log on to the site from a computer, you will be able to see how well you have done, and transform the cards into a test by clicking on the "Flashcards" tab as shown below. The questions are multiple choice or true/false, avoid the "Type the answer" questions by unselecting at the top left, and regenerating the quiz:

(Ignore my 3%, I had only done one!)

The quiz then looks like this, be warned, they are pretty difficult!

You can work online in exactly the same was as on your mobile, but only the online version offers you the quiz version. The quizzes are good, and there is an option to change the question style at the top left. You can track your progress online, and if these are useful, I will write some more over the next few weeks to help with the new modules. 

Please let me have feedback, I know it is close to the exam, but these would be handy for last minute revision, and as they work on your phones/iPods without an internet connection, just think about all the fun places you can revise such as the bus, the coffee shop, etc, in fact, send me a picture on the Facebook Page of you revising in an unlikely place to win a small prize. 

Dont forget the online revision tomorrow, and have a good weekend!


PS. DIrect links once you have an account:

Rivers Terminology: http://s.tudy.it/twlnsp
Population Terminology: http://s.tudy.it/twlnsp
Skills Test: http://s.tudy.it/twzznk