How you can Use Statistical Techniques to Collect and analyze Data
These are techniques of collecting, recording, presenting and analyzing statistical data. Uses of statistical methods in geography
To summarize data in a way that it can be understood easily.
For precision and objectivity in explaining geographical phenomena.
To show or prove any relationship between phenomena.
To show changes in a phenomena over time. To explain geographical phenomena e.g. climate.
For prediction of future i.e. population data. Used for planning e.g. census figures.
Types of data
1. Primary data - original data/first hand. It is obtained from the field.
2. Secondary -available in stored sources e.g. text books, maps and videos.
Methods of data collection
(1) Taking measurements
- Methods of taking measurements in the field includes:
Using instruments such as metre rule, tape measure, etc.
Estimating heights and distances
- - Pacing to estimate land area.
- Data is accurate.
- quick to collect data.
- inaccuracy of some data
(ii) Content analysis
Obtaining data from secondary sources e.g. text books.
- Easy to collect data where information is already analysed.
Method is cheap as publications are-available.
- Information available could be biased or prejudiced.
- Data may be outdated or irrelevant.
There are three types of sampling techniques
- Random sampling Where distribution of phenomena is random.
- Systematic sampling Where phenomena is evenly distributed.
- Stratified sampling Where samples are grouped or classified. e.g. t Age, size of farms etc.
- It is less expensive.
- It saves time.
- It limits bias.
Poorly selected sample may be misleading.
Not suitable for unevenly distributed phenomena.
Involves direct visual observation.
• First hand information
• Data is reliable
• ' Saves time.
• It is subjective- based on personal observation.
• It's expensive and tiresome due to travelling.
• Can be hindered by bad weather.
• Visually impaired people may not be able to use the method.
• Can only be used or collect the present data.
Data is obtained by asking people questions.
• First hand information is obtained.
• One seeks clarification from respondents for ambiguous answers.
lots of information may be obtained.
• Promotes good relations with respondents.
• Can be used to get information from -I:1 :rate people,
• Language barrier.
• Expensive- involves a lot of movement.
• Time consuming
• Information may be unreliable due to forgetfulness.
• Information may be subjective.
• Wrong information may be given.
(iii) Administering of questionnaire
Involves use of pre-set questions to gather information.
Questions can be open- ended questions or closed questions.
• Clarification can be sought for unclear answers.
• Easy to compare responses for different. respondents. •
• First hand data.
• A lot of information can be collected.
• Saves time since all respondents are served with questionnaire at the same time.
• Inaccurate data may be obtained.
• Difficulties in analysing data with different answers.
• Some people may refuse to send back the questionnaires.
• Not useful where respondent is illiterate.
Methods of data recording
1. Photographing/filming/video taking.
3. Field sketching/mapping
5. Tape recording
6. Taking notes
7. Filling in questionnaires
Methods of analysing data
(i) Calculation of percentages
(ii) Calculation of dispersion - ranges e.g. diurnal range of temperature.
(i) Statistical tables - Data is arranged in rows and columns according to categories to which it belongs.
• Easy to obtain and locate accurate data.
• Easy to compare.
■ Saves time and space.
• Easily understood because it is arranged in clear and orderly manner.
• Interpretation may be difficult where there is large range of values.
• Takes time to interpret.
• Tables are not appealing to the eyes.
(ii) Statistical graphs
They are drawings consisting a lines or bars showing relationship between two sets of values.
(a) Line graphs
(b) Bar graphs
(c) Age and sex graphs
- Simple line graphs
- Comparative (graph) lines graph
- Compound lines graphs
- Divergence lines graph
Simple line graph
- It shows relationship between two variables. Construction
Draw x and y axis on graph paper.
Choose suitable scale for variable.
Plot values accurately using small faint visible dots.
Join the dots by a smooth curve.
Characteristics of line graphs
(1) Have a scale - vertical and horizontal.
(ii) Vertical scale starts at o/origin.
(iv) Have a title.
(v) Labelled axis.
Group line graphs
They involve drawing of more than one line on the same statistical graph. They are drawn for the purpose of comparison.
The steps followed during construction are similar to the ones for simple line graphs.
Use different types of line for. different variables i.e. broken and continuous lines.
Write name of the variable represented along the time.
Reduce congestion of lines by choosing a fairly large scale.
Compound line graphs
- It is used to analyse the total and individual outputs of specific variables.
- e.g. Kenyan exports and imports. -Construction
- Draw X and Y axis. Y axis should begin at zero. Choose s suitable scale - should be based on the highest and lowest values.
Plot values on the graph for the least variable. Join the dots.
Draw the second graph above the first graph. To draw the second graph, add the value of the second valuable to the first.
- Do likewise for the rest.
• Shows total values easily.
• Gives good visual impression.
• Difficult to get value of individual component.
• Involves a lot of work.
Also known as columnar graphs.
Used to represent data that is not continuous. They includes
• Group (comparative)
Simple bar graphs
(I) Choose suitable scale for horizontal and vertical axis.
(ii) Plot the values for each bar in the middle of the column.
(iii) Draw a horizontal line through the plotted dot to join right and left vertical lines.
(iv) Shade the bars uniformly.
Points to note
• The bar graph should have title.
• Axis should be labelled.
• All bars should start at zero.
• Bars should have the same width.
• Gap between bars should be the same.
Comparative bar graphs
These are bar graph columns grouped together for the purpose of comparison
• Draw the axis
• Choose suitable scales
• Draw bars touching each other for each group. leave space.
• Before drawing the next group of bars.
• NB: The same order of component should be used in all groups.
• Have good visual impression
• Easy to construct
• Easy to read
• Difficult to follow the general trend of individual component.
• They do not compare totals easily.
Compound bar graphs/cumulative bar graphs This is type of graph where individual bars are subdivided to show different parts.
The lengths represent value of different components.
• General rules of constructing simple bar graphs are applied.
• First draw the bar column representing the total value of different parts/Add totals upwards.
• Sub-divide the bar according to the value of different parts.
• NB: The same order of sub-divisions should be followed for all bars.
• Spaces of same widths are left between bars. Also space at the left and right corner of X-axis.
• Easy to read and interpret
• Easy to construct
• Difficult to establish value of individual part'se
- Divided circles
- Divided proportional circles
- Gives goad visual impression
- Easy to read and interpret
- Difficult to determine the value represented by each.segment.
Involves a lot of work to calculate and draw.