Collecting Quantitative

DataBy:

Zainab Aidroos

Making questionnaires

Interviews

observing people

The outline

-Who will you study? -The unit of analysis

-The population and the sample-Types of quantitative sampling

strategies-What information will you collect

-The uses of instruments-How to decide what types to choose in

your research

Who will you study

Identify people and places you plan to

Study This involves determining

1 -individuals 2 -entire organizations ex: schools

3 -combination

Decide what type of people or organizations you will actually studyAnd

How many you will need for your research.

Identify your unit of analysis

Who supplies the information ? Students, teachers, parents and some

combination of these individuals or entire schools.

At this early stage ,you need to decide at what level the data needs to be gathered .ex: individuals , family, school

school district.This level is referred as the unit of

analysis.

Multiple levels such as individuals and schools

Or One level such as principals on

schools.

Specify the population and sample

Select individuals who are representative of the entire group.

selection of Representative: refers to the individuals from a sample of a population ,enabling you to draw conclusions from the sample about the population as a whole .

Population :a group of individuals who have the same characteristic .

Examples:Populations

All English teachers in high schools on one city

Sample:

A sample of high school teachers who teach English from different schools in one city . .

Researchers decide what type of sampling Depending on three factors:

they seek for their studies 1-Amount of rigor

2-The characteristics of the target population

3-The availability of participants.

Types of quantitative sampling strategies:1-Probability sampling

1-simple random sampling: The researchers select participants

or units such as schools for the sample

So any individual has the probability of being selected from the population .

The intent of simple random sampling is to choose individuals to be sampled who will be representative of the population.

The typical procedure used in simple random sampling is to assign a number to each individual or site in the population and then use a random numbers table, available in many statistics books, to select the individuals for the sample.

See page 153

Systematic sampling

Choose every individual or site in the population until you reach your desired sample size .

More convenientBecause individuals do not have to

be numbered and it does not require a random numbers table.

2-Stratified Sampling Another type of probability sampling

The researchers divide (stratify) the population on some specific characteristic (stratum)of the population. e.g, females and males.

*It is used when the population reflects an imbalance on a characteristic of a sample .

**It is also used when a simple random sampling procedure would yield fewer participants in a specific category (e.g, females) than you need for rigorous statistical

analysis .

The procedure for selecting a stratified sample consists of 1-dividing the population by the stratum e.g, men and women

2-sampling within each group in the stratum e.g, women first and then men.

So that the individuals selected are proportional to their representation in the total population.

3-Multistage Cluster Sampling *A form of probability

The researcher chooses a sample in two or more stages because:

&The researchers can not easily identify the population

Or

&&The population is extremely large.The stages: 1-choosing randomly the districts

2-Sampling randomly within the districts

Nonprobability Sampling

Select individuals because they are available , convenient, and represent some characteristic the investigator seeks to study.

Two popular approaches :convenience and snowball approaches

Convenience Sampling

The researcher selects the participants because they are willing and available to be studied.

Snowball Sampling

Alternative to convenience sampling The researcher asks participants to

identify others to become members of the sample .

Sample Size

Select as large as possible from the population.The larger the sample, the less the potential error that the sample will be different from the population.Sampling error: the difference between the sample estimate and the true population score.

What information will you collect?

*Identification of the participants *A Procedure of gaining permission

*Identifying the variables in your questions or hypotheses and finding definitions for them

*Considering types of information that will help you assess these variables.

Specify variables from research questions and hypotheses For the purpose of determining what data you need

Define each variable

Operational definition: the specification of how you will define and measure the variable in your study .

Considering types of information that

will help you assess these variables.Identify types of data that will

measure your variables. Researchers collect data on

instruments.An instrument: is a tool for measuring ,

observing, or documenting quantitative data, e.x: a test, questionnaire, tally sheet, observational checklists, inventory or assessment instrument .

The uses of instruments

*Measure achievement*Assess individual ability

*Observe behavior*Develop a psychological profile of

an individual *Interview a person

Performance Measures

*To assess an individual's ability to perform on an achievement test, intelligence test ,aptitude test, interest inventory or personality assessment inventory.Drawbacks:

1-It does not measure individuals attitudes2-Performance data may be costly

3-Time consuming to gather4-Potentially biased toward specific cultural

groups

Attitudinal Measures

*To measure feelings toward educational

e.g., assessing positive or negative )topicsattitudes toward giving students a choice of school to attend).

*Unbiased questions

*They don’t provide direct evidence of specific behaviors.

Behavioral Observations

Selecting an instrument or using a behavioral protocol on which to record a behavior, observing individuals for that behavior and checking points on a scale

that reflects the behavior.(checklists)

To identify an individual’s actual behavior,

Factual Information

Or personal documents consist of numeric, individual data available in public records.

Examples :grade reports

School attendance recordsStudent demographic data

Census information

Web-Based Electronic Collection*Surveys

*Gathering interview data*Using databases for analysis

*Provides an easy ,quick form of data collection

Disadvantages:Limitation involving the use of list

serves and obtaining of e-mail addresses .

Lack of the a population list.The questionable representativeness of the sample data.

How to decide what types to choose

*What am I going to learn about participants from my research questions?

*What information can you realistically collect?

*How do the advantages of data collection compare with its disadvantages?