 Collecting Quantitative  Data  By: 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 study And 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 convenient  Because 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 attitudes 2-Performance data may be costly 3-Time consuming to gather 4-Potentially biased toward specific cultural groups

Attitudinal Measures  * To measure feelings toward  educational e.g., assessing positive or negative )topics attitudes 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 records  Student 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 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?