Data Analysis Section

TURNING FIELD DATA INTO RESULTS YOU

CAN ANALYSE

OR

AN IDIOTS GUIDE TO DRAWING GRAPHS

FOR MS RICHARDS GCSE

GEOGRAPHY CLASS

Deposition inriver channel

Direction of flow

Grassand moss Tree roots,

stabilising bank

Two pollarded Beechtrees with the tree roots, stabilising bank

erosion

PollardedHornbeamTree on meander bend

Un vegetated area

woodland

River cliff

Beech Tree

VariableSite Number

1 2 3 4 5

Water width (m) 0.20 0.22 0.50 0.82 1.60

Wetted Perimeter (m) 0.35 0.36 0.55 0.98 1.90

Water Depth Left Hand side (m) 0.05 0.06 0.05 0.06 0.10

Water Depth Middle (m) 0.06 0.08 0.07 0.15 0.15

Water Depth Right Hand side (m) 0.04 0.09 0.05 0.20 0.12

Float Time (seconds) 8 6 5 3 2

Gradient (degrees °) 3 2 1 1 0

All tables should:• be clear and concise• be fully labelled and have a title• show one type of data e.g. raw data (data collected in the

field)• show units of measurement• not include too much information• summarise or put secondary data into additional tables

e.g. means only have totals in if they are relevant

Use a line graph to show:• continuous measurements e.g. rate of change over time or distance• results that are sequential• high and low value

Example: Loughton Brook showing change in velocity with discharge

Change in velocity w ith distance downstream,Loughton Brook 05/03/02

0.00

0.10

0.20

0.30

0.40

0.50

0 500 1000 1500Distance from source (m)

Vel

oci

ty (

m/s

)

Bar charts:• show frequency of items in a category e.g. place name or

species• the categories are on the horizontal axis• have one quantitative scale showing the observed data

(frequency) on the vertical axis• a gap is left between each category• use different shading for each category as they are

discrete• can be used for up to 3 sets of data on one graph

Example: Pebble Survey

HISTOGRAMS MUST:• Histograms have two quantitative scales the vertical scale shows

frequency, the horizontal axis represents size classes or values e.g. pebble sizes, age categories.

• The area of the block, not the height gives the observed frequency• Choose a suitable scale (they do not have to start at 0) this should be

continuous• Each ‘block’ should join the ones next to it• Use the same colour for each block as they are part of one sample• Use for up to three sets of data

Pebble Size at site 1Loughton Brook 10/11/04

0

2

4

6

8

10

12

0.0-

0.9

1.0-

1.9

2.0-

2.9

3.0-

3.9

4.0-

4.9

5.0-

5.9

6.0-

6.9

7.0-

7.9

Pebble size (cm)

Fre

qu

en

cy

Use when you have two observations (variables) you want to compare(correlation)

Positive Negative

The graph showsthe relationship

between the variables

• Each variable goes on an axis:• the independent variable e.g. distance goes on the horizontal

axis• the dependant variable e.g. average water depth goes on the

vertical axis• Each pair of figures is plotted as a single point using the

observed data• The more points the reliable the graph (Use all 12 sets of

data)• The points are not joined up, a line of best fit is used to

indicate the trend

Average depth of river and distance downstream, Loughton Brook 11/10/04

0

0.05

0.1

0.15

0.2

0.25

0.3

0 100 200 300 400 500 600

Distance downstream (m)

Ave

rag

e w

ater

dep

th (

m)

Think about what other variable you could show.

Some examples could be channel width, speed of flow, etc. This is a good way to analyse changes in the river.

• The width of the feature is measured and depth or height measurements are taken at regular intervals

• The more measurement the more accurate the finished cross section

• The data is plotted on a graph, where possible both scales (horizontal and vertical) should be identical.

• Care must be taken to avoid or account for vertical exaggeration

• The points on the cross section should be joined by hand, not ruler as they are not straight lines in reality

Cross sections are used to indicate change in shape and size of a feature between locations. They can be used to calculate area and as a base for other related information.

Use Excel to draw your cross sections. Don’t forget to calculate all the data you need before you start. If you copy the class data into excel you could get it to calculate the equations for you.

Cross section of Loughton Booksite 1 16/02/05

-20

-15

-10

-5

0

0 20 40 60 80 100

Width of river (m)

Dep

th o

f w

ater

(cm

)

Remember you will have to do more than one cross section as you should be showing the changes as you travel downstream