Collection, Summarization and Presentation of Data

Introduction

Data can be collected in different ways. It can be obtained from original data or from previous students.

Methods of Collecting Data

The methods of collecting data are:

1. Direct or interview method. This is a personal communication with the individual you want to interview.

2. Indirect or questionnaires method. This is done by sending questionnaires to the person from whom you would like to get the information.

3. Registration method. Utilizing existing records from various agencies.

4. Observation method. This can be done directly or indirectly.

5. Experiment method. This is done with the participation of a certain researcher. In other words, there is a human intervention occur during the process of data collection.

Two Documented Sources of Data

1. Primary Data. Data documented by the primary source.

2. Secondary Data. Data documented by a secondary source.

Sampling Techniques

The study of the entire population of interest in some situations is impractical or even impossible to include the entire population. Thus, take a part of a population, the so-called sample.

Sampling

Sampling is the process of selecting the sample or the study units from a previously defined population.

Sampling Error

Sampling error is the difference or deviation of the sample from the population with respect to the characteristics of interest in the study.

Sampling Frame

The list of units from which the sample were drawn in any sampling procedure.

Sampling Procedure

Sampling procedure refers to the manner in which the members of the population are selected as part of the sample. These are classified into probability or random sampling and non-probability sampling procedures.

Sample Size Determination

An important aspect of the sampling design is the sample size. The number of members that you include in the study must not be too small in order to come up with reliable estimates. According to some researchers and statisticians suggest, Slovin’s formula is an alternative approach to computing the sample size. The formula is given below;

Where;

n – the sample size N – the population size e – the desired margin of error

Probability Sampling Procedures

These comprise all sampling methods done when there is a sampling frame which ensures that all the probable sampled have an equal chance or probability of being selected for the study.

Types of Probability Sampling Procedures

Simple Random Sampling

This is the basic method on which all other methods of probability sampling are built. Each member of the population has an equal and independent chance of being selected.

Systematic Sampling

This is done by selecting a sampling interval k and using the sampling frame, the researcher selects every kth member of the population beginning at some random point and cycling through the list.

Stratified Sampling

The members of the population are classified into non-overlapping groups or strata on the basis of characteristics to be properly represented in the sample.

Cluster Sampling

This is usually used in studies of huge populations where the sampling frame may be too large to study or too time-consuming that is better to divide them first into clusters or groups and randomly select a sample cluster of choice.

Multistage Sampling

This is usually done in big community-based studies in which selection of the sampling unit is done by stages.

Non-probability Sampling Procedures

These are methods that do not include random sampling at some stage in the process. Further, these are applicable when there is no sampling frame available.

Types of Non-Probability Sampling Procedures

Convenience Sampling

In this method, the sample consists of elements that are most accessible or easiest to contact.

Judgement or Purposive Sampling

In this method, the researcher chooses a sample that agrees with his/her subjective judgment of a representative sample.

Quota Sampling

Is the non-probability sampling wherein the researcher just sets a quota or number of sampling units to be included in each grouping but uses convenience sampling to select the units within each grouping.

Snowball Sampling

Also called chain referral and referential sampling. This is used to find members of a group not otherwise visibly identified.