**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.

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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.

Counting

Estimating heights and distances

- - Pacing to
estimate land area.

Advantages

- Data is
accurate.

- quick to collect
data.

Demerits

- inaccuracy
of some data

(ii) Content analysis

Obtaining data from secondary sources e.g. text books.

Advantages _

- Easy to
collect data where information is already analysed.

Method is cheap as publications are-available.

Disadvantages

- Information available could be biased or prejudiced.

- Data may be outdated or irrelevant.

(iii) Sampling

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.

Advantages

- It is less
expensive.

- It saves
time.

- It limits
bias.

Disadvantages

Poorly selected sample may be misleading.

Not suitable for unevenly distributed phenomena.

(1) Observation

Involves direct visual observation.

Advantages

• First hand
information

• Data is
reliable

• ' Saves time.

Disadvantages

• 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.

(ii) interviewing

Data is obtained by asking people questions.

Advantages

• 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,

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Disadvantages

• 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.

Advantages

• 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.

Disadvantages

• 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.

2. Tabulating

3. Field
sketching/mapping

4. Tallying

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.

Advantages

• 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.

Disadvantages

• 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.

Graphs includes

(a) Line graphs

(b) Bar graphs

(c) Age and sex
graphs

Line graphs

They include;

- 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.

NB:

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.

Advantages

• Shows total
values easily.

• Gives good
visual impression.

Disadvantages

• Difficult to
get value of individual component.

• Involves a
lot of work.

Bar graphs

Also known as columnar graphs.

Used to represent data that is not continuous. They includes

• Simple

• Group
(comparative)

• Compound

• Divergence

Simple bar graphs

Construction

(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

Construction

• 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.

Advantages

• Have good
visual impression

• Easy to
construct

• Easy to read

Disadvantages

• 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.

Construction

• 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.

Advantages

• Easy to read
and interpret

• Easy to
construct

Disadvantages

• Difficult to
establish value of individual part'se

Statistical charts

They include:

- Divided circles

- Divided proportional circles

Advantages

- Gives goad visual impression

- Easy to read and interpret

Disadvantages

- Difficult to determine the value represented by
each.segment.

Involves a lot of work to calculate and draw.