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Collecting Quantitative


Collecting Quantitative Data By: Zainab Aidroos * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * Making questionnaires Interviews observing people ... – PowerPoint PPT presentation

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Title: Collecting Quantitative

  • Collecting Quantitative
  • Data
  • By
  • Zainab Aidroos

Making questionnaires
Interviewsobserving 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

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 strategies1-Proba
bility 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
  • 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

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
  • The larger the sample, the less the potential
    error that the sample will be different from the
  • 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
  • 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

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

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

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 dont provide direct evidence of specific

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 individuals 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 e-mail addresses.
  • Lack of the a population list.
  • The questionable representativeness of the sample

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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?

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