Main Topics • Definition of Variable • Definition of population• What is sample?• Sample and population• What is sampling and sampling methods• Instrument and instrumentation

Understanding of variables

• A variable is a measurable characteristic that varies.

• A variable is any characteristic or quality that varies among the members of a particular group.

Understanding of variables (cont)

A variable is a concept-a noun that stands for variation within a class of object, such as

• Age• occupation• income, • marital status• Number of children• gender• race• achievement

Type of Variable

Dependent and Independent Variable

• An independent variable is a variable presumed to affect or influence other variables.

• A dependent variable (or outcome) is a variable presumed to be affected by one or more independent variables.

Definition of Population

A population is the group to which the results are intended to apply.

The term “population” is as used in research, refers to all the members of a particular group.

It is the group of interest to the researcher, the group to whom the researcher would like to generalize the results of a study.

Examples of Population

All high 10th-grade students in the united sates All elementary school gifted children in the state of

California All first-grade physically disabled students in Omaha

who have participated in preschool training First, population may be virtually any size and may

cover almost any geographical area. Second, the entire the researcher really would like to

generalize is rarely available

Sample and Population

A sample is a group in research study on which information is obtained.

The sample is smaller than the population. The small group that is observed is called a sample,

and the larger group about which the generalization is made is called a population

A population is defined as all members of any well-defined class of people, events or objects. A sample is a portion of a population.

Steps in Sampling

Target populationThe population that the researcher would like to generalize

to is referred to as the target population

Accessible population Since it is usually not possible to deal with the whole of the

target population, one must identify the portion of the population to which one can have access-called the accessible population.

Sample From the accessible population, one selects a sample in

such a way that it is representative of the population.

Examples

Target populationAll fifth-year students enrolled in teaching training

programs in the United States. Accessible population All fifth-year students enrolled in teaching-training

programs in the state university of New York.Sample Two hundred fifth-year students selected from

those enrolled in the teacher training programs in the State university of New York.

Sampling Methods

There are two methods are commonly known in social science research. These are:

1. Random Sampling

2. Non-random sampling

Random Sampling

Random sample is one in which each and every member of the population has an equal and independent change of being selected)

Example:• The population is all 300 eight-grade

students enrolled in general math at central Middle school.

Type of Random Sampling

The four types of random sampling most frequently used .These are:

• Simple random sampling • Stratified sampling• Cluster sampling • Systematic sampling

The major forms of non-random sampling are:

• Purposive sampling

• Convenience sampling

Type of Non-random Sampling

Purposive Sampling

• Purposive sampling is referred to as judgment sampling. • Sample elements are judged typically or chosen from the population.

Purposive sampling is a selective sampling because the individual or respondent has special qualification.

• Much of the sampling in qualitative research is purposive. Purposive sampling is appropriate in three situations.

• First, If a researcher wants to use content analysis to find cultural themes. In that case, the researcher needs to select a community.

• Second, a researcher may use purposive sampling if he or she wants investigate for a special group. If the researcher wants to conduct research, he or she needs to be selective. It is impossible to list all prostitute and sample randomly from the list..

• Third, a researcher may use purposive sampling when he or she wants to identify particular types of cases for in-depth investigation.

Non-random Sampling (cont’d)

Instrument and Instrumentation

• Any device/material that the researcher uses to collect data throughout the research is called instrument.

• The device the researcher uses to collect data is called an instrument.

• The device can be a pencil and paper test, interview, a questionnaire, or a rating scale.

• The whole process of collecting data is called instrumentation.

Data Analysis (Qualitative)

Instruments for qualitative study are :

Interview Paper Pencil Tap recorder Observation

Qualitative Data Analysis (Cont..)

The transcribed interviews with the field notes will be examined and classified into the themes.

The tape-recorded interviews were fully transcribed and great care was taken to protect the secrecy of respondents.

The researcher followed the same sequence for the observation. When staying in the field, the researcher quickly write down the notes. To gathering information depends on the researcher’s understanding of the

research problem and the subject under the study.

Quantitative Data Analysis

Instrument for Quantitative data are :

• interview,

• a questionnaire

• or a rating scale

• Software (SPSS)

Quantitative Data Analysis (Cont…)

Quantitative data can be analyzed using the Statistical Package for the Social Science (SPSS) program.

The questions can be coded before being entered into the computer to be analyzed.

For the simple descriptive study frequencies, standard deviation, mean and percentages, minimum and maximum value can be largely used for research .