Statistical methods

Statistical methods

methods of collecting data

sampling Examining by taking a sample -a part representing the whole (population).

Types of Sampling

1. Random Sampling

Selection of members of a group haphazardly where every item has an equal chance of being selected e.g. to select 5 students to go for a tour from a class:

• Class members write their names on pieces of paper

• They are folded and put in a basket

• The basket is shaken and fives papers are taken out

Systematic Sampling

Selection of members of a sample from an evenly distributed phenomena at regular intervals e.g. after every 10 items/members.

Stratified sampling

Selection of members of a sample by breaking the population into homogenous groups e.g. to select 6 students to go for a tour:

• Break the class into boys and girls

• Select 3 student from each group by random or systematic sampling

• Combine units from each group to form the required sample.

Advantages

a) It’s less expensive

b) It saves time

c) It avoids bias

Disadvantages

a) A poor selected sample can lead to misleading information

b) Systematic sampling to an evenly distributed population

Tabulation

-Drawing of tables and filling in data systematically e.g. weather recording sheets.

M

Methods of Recording Data

-Methods off storing information to avoid losing it

 Note Taking

-Writing in a note book what is being observed, answers during interviews and then notes are compiled in school or office when writing report.

2. Filling In Questionnaires

-Filling answers in questionnaires which are responses from a respondent by an interviewer or respondent himself which he/she then sends back.

3. Tallying

-Making 4 vertical or slanting strokes and the 5th across the 4 to record data obtained by counting or measuring similar items.

Tape Recording

-Recording image of an object or landscape on a film which is processed to get a photograph then the photographs are labelled to avoid mix up during storage.

Labelling samples

-Recording conversations during interviews on audio tapes using a tape recorder.

Permission should be got from the respondent to record his/her responses.

Field Sketching

Summarising information observed in the field by making a rough drawing of landscape and labelling the essential information.