M2: Basic Concepts of Sampling Design

• Data collection is the process of gathering and measuring information on variables of interest, in an established systematic fashion that enables one to answer stated research questions, test hypotheses, and evaluate outcomes.
• Sources of Data

  • Primary Data
  • Secondary Data
• Primary data are data which are collected fresh and for the first time and thus happen to be original in character.
• Secondary data are data which have been collected by someone else and which have already been passed through the statistical process.
• Collection Methods for Primary Data

  • Direct/ Interview Data
  • Indirect/ Questionnaire Data
  • Experiment Data
  • Observation Data
• The interview method is the collection method with oral verbal communication where the interviewer asks questions to the respondent.
• Types of Interviews

  • Personal
  • Telephonic
  • Structured
  • Unstructured
  • Individual
  • Group
  • Clinical
  • Selection
• Personal is a type of interview where questions are asked in face-to-face contact with the interviewee.
• Telephonic is a type of interview where the interviewer samples in telephone or in virtual conferencing platforms.
• Structured is a type of interview where there are a set of predetermined questions.
• Unstructured is a type of interview that do not follow a predetermined questions.
• Individual is a type of interview in a one-to-one setup.
• Group is a type of interview with more than two individuals are being interviewed.
• Clinical is a type of interview concerned with feelings or consultations with health concerns with a health professional as the facilitator of the interview.
• Selection is a type of interview which is done for the selection of people for certain jobs.
• A questionnaire is a self-administered research instrument that can be done by mail or in a group setting such as classroom.
• Types of Question

  • Open-ended Question
  • Close-ended Question
• An open-ended question is a type of question that does not include response categories.
• A close-ended question is a type of question that includes a list of response categories from which the respondent will select his answer.
• Validity refers to the extent that the instrument measures what it was designed to measure.
• Content validity is a validity method that measures the extent to which the items that comprise the scale accurately represent or measure the information that is being assessed.
• Construct validity is a validity method that measures what the calculated scores mean and if they can be generalized.
• If convergent validity exists, construct validity is supported.
• Criterion-related validity is a validity method that measures how well the scores from the instrument predict a known outcome that is expected to predict.
• Reliability refers to the extent that the instrument yields the same results over multiple trials.
• Test-retest is a reliability method that administers the same instrument to the same sample at different points in time.
• The alternative form method is a reliability method that requires two different instrument consisting of similar content.
• The split-halves method is a reliability method in which the number of items in the scale is divided into halves and a correlation is taken to estimate the reliability of each half of the test.
• Experiment is a method of collecting data where there is a direct human intervention on the conditions that may affect the values of the variable of interest.
• The independent variable is a variable in an experimental study that is manipulated by the researcher.
• The independent variable is also called as the explanatory variable.
• The resultant variable is called the dependent variable or the outcome variable.
• The treatment group is the group that receives the treatment whose effect the researcher is interested in.
• The control group is the group that receives either no treatment, a standard treatment whose effect is already known, or a placebo.
• In an experimental study, the researchers manipulate one of those variables and try to determine how the manipulation influences other variables.
• In a true experiment, participants are randomly assigned to either the treatment or the control group.
• In a quasi-experiment, it lacks the random assignment to treatment and control groups.
• A research design includes the structure of a study and the strategies for conducting the study.
• In experimental designs, having R means the study is randomized or the subjects are randomly selected to treatment group.
• In experimental designs, O means the observation of testing.