Quantitative Research Vocabulary

Vocabulary of Quantitative Research

  • Course: COS 355

  • Instructor: Nick Carcioppolo, Ph.D.

Populations & Samples

  • Population: Refers to the entire group that research aims to understand or draw conclusions about.

  • Sample: A subset of the population used to represent the population in a study.

Descriptive vs Inferential Statistics

  • Descriptive Statistics:

    • Purpose: To summarize and describe the characteristics of a dataset.

    • Example Question: "Do you enjoy the films of Nicolas Cage?"

  • Inferential Statistics:

    • Purpose: To infer or draw conclusions about a population based on sample data.

    • Example Question: "If someone enjoys the films of Nicolas Cage, what else can we infer about him/her?"

Constructs

  • Definition: Constructs are abstractions generalized from particulars; they are ideas that researchers form to summarize observations about things that cannot be directly observed.

Classifications of Variables (Constructs)

  • There are two broad classifications:

    • Categorical Variables:

    • Definition: Participant responses are divided into categories that do not have a logical order.

    • Examples: Colors, race/ethnicity, treatment vs. control, types of whiskey.

    • Quantitative Variables:

    • Definition: Participants are placed on a continuum that indicates different amounts of a characteristic.

    • Examples: Level of agreement, liking, attitude, certainty of belief.

Levels of Measurement

  • Definition: The scale used to measure constructs impacts the type of statistics utilized for data analysis (e.g., mean vs. mode) and hypothesis testing (e.g., correlation vs. t-tests).

  • Nominal Level:

    • Definition: For categorical data where numbers assigned to categories are indices without real meaning.

    • Characteristics: These data are typically represented by counts and often analyzed by mode.

    • Example in text: "The sample was largely female (n = 60; 74%)."

  • Ordinal Level:

    • Definition: For numerical data where numbers suggest order but do not provide precise measurements of distance between categories.

    • Characteristics: Reflects the rank order of categories.

  • Interval Level:

    • Definition: For numerical data where numbers not only suggest order but assume equal distances between categories (e.g., temperature in Celsius).

  • Ratio Level:

    • Definition: For numerical data that includes an absolute zero point, thus allowing for the comparison of absolute magnitudes (e.g., weight, height).

    • Characteristics: Incorporates all properties of interval level as well as an absolute zero point.

Social Science Constructs Measurement

  • Common levels of measurement for social science constructs typically include ordinal scales, especially in surveys measuring attitudes or traits, exemplified by Likert scales.

  • Example in survey format from a measure of Machiavellianism:

    • Strongly Disagree (1)

    • Disagree (2)

    • Undecided (3)

    • Agree (4)

    • Strongly Agree (5)

What is Measurement?

  • Definition: Measurement is the process of determining the existence, characteristics, size, and/or quantity of change in a variable through systematic recording and organizing of observations.

Quantitative Measurement

  • Definition: It consists of rules for assigning numerical values to units (people) to indicate the relative level/degree of a variable that is present.

  • Example: Belief in the Supernatural

    • Conceptual Definition: "Belief in one or more extraordinary phenomena that defy explanation according to current scientific understanding of natural law."

    • Operational Definition: Utilization of the Paranormal Belief Scale or Supernatural Belief Scale (refer to Survey for details).

Quantitative Measurement Scoring Rules

  1. Reverse Scoring: For the odd-numbered items, inverse the score (e.g., for items sb1r, sb3r, sb5r, … sb91r; 1=5, 2=4, 3=3, 4=2, 5=1).

  2. Summation: Total the scores for all items (sb1 + sb2 + sb3 + … sb20).

  3. Average Calculation: Divide the total score by the number of items (20) to revert scores to the original 1-5 scale.

Hypothesis vs Research Question

  • Difference: A hypothesis is a specific, testable prediction about the expected outcome of a study, while a research question is a broad query that the study seeks to answer.

  • Directionality: Refers to whether the hypothesis predicts the direction of the relationship between variables (positive/negative) or simply states a relationship without specifying direction.

Independent and Dependent Variables

  • Independent Variable: The causal variable that is manipulated by the researcher to observe its effect.

  • Dependent Variable: The effect variable that is measured to see the impact of changes in the independent variable.

  • Key Characteristics: Independent variables serve as predictors of dependent variables, thus being critical to the design and analysis of quantitative research.