Introduction to Research Design and Statistics

Preliminary Issues

The question of where to start is always difficult. We will begin by defining some terms so that we have a vocabulary with with to begin our discussions concerning research methods and statistics.

What is research?

  • Research is a systematic attempt to provide answers to questions.
  • As such, research may be basic or applied.

    What is a statistic?

  • A statistic is a value that is computed on a sample.
  • A parameter is a value that is computed on a population.

    Why use samples?

  • Analyzing samples is more cost effective than analyzing populations,
  • And if done correctly just as accurate.
  • Just remember the next time the doctor wants to do a blood test, would you want him to test all of your blood or just a small sample?

    What is statistics?

  • Statistics is the science of collecting, organizing, and interpreting numerical facts called data.
  • Data - Data are numbers with a context.
  • Descriptive Statistics/Exploratory Data Analysis
  • Inferential Statistics
  • Probability - the chance or likelihood that an event will occur.
  • Bias - Systematically favoring certain outcomes.

    Riddle: What is a statistician?

  • A researcher who draws mathematically precise lines from unwarranted assumptions to foregone conclusions.

    What is research validity?

  • Internal vs External Validity

    Internal Validity -- A research study or experiment has internal validity if the outcome is a function of the variables that are measured, controled or manipulated in the study. Did in fact the experimental treatments make a difference in the study?

    External Validity -- A research study or experiment has external validity if the results obtained would apply to other similar programs or approaches.

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    Phil Ender, 30Jun98