An observational study, as supposed to an experimental study is a type of study that investigators observe the effect of an intervention without assigning it to the subjects at random.  That is, the subjects choose their own treatment/ intervention.  

Observational studies may prove to be less costly that RCT's, given that the investigator need not actively change the behavior of the subjects


Observational Studies

A Randomized Controlled Trial (RCT) or a Controlled Experiment is a method to eliminate unmeasurable confounders effect on causal inference by implementing an intervention on a randomly selected group of individuals (treatment/intervened group) while keeping other individuals unchanged (controlled group, placebo, not-intervened group) to observe the changes in outcomes due to the intervention effect. The RCTs are intended to "disarm" confounders (confounding variables).

Randomized Controlled Trial (RCT) = Controlled Experiment

Qualitative researchers often criticize quantitative methods for overlooking the rich complexity of human behavior and experience. They argue that quantitative approaches tend to oversimplify phenomena by focusing only on answering simple questions about easily quantifiable variables. However, quantitative researchers acknowledge this oversimplification, utilizing it as a deliberate strategy to uncover broad, general principles of human behavior.

Criticisms of Quantitative Research

Group research is the most common quantitative research approach in psychology, characterized by studying a large number of participants and combining their data to draw general conclusions about human behavior. In this methodology, researchers primarily analyze and interpret behavior by examining aggregated statistical metrics across the entire sample, such as group means and standard deviations, rather than focusing on the detailed behavior of individual subjects.

Group Research

The primary strength of quantitative research lies in its ability to provide precise answers to specific, tightly focused research questions and to draw broad, general conclusions about human behavior. By employing statistical analysis on large samples, this methodological approach allows researchers to uncover general behavioral trends, such as the overall tendency of individuals to obey authority figures or comparing traits across demographic groups.

Strengths of Quantitative Research

Single-subject research, frequently referred to as small-$$n$$ design (where $$n$$ represents the statistical symbol for sample size), is a quantitative methodology that involves studying a small number of participants and focusing closely on each individual's behavior. Despite its name, this approach typically investigates between two and ten participants rather than just one. Serving as a crucial alternative to group research, particularly in applied areas of psychology, single-subject research seeks to comprehend objective behavior by utilizing strict experimental manipulation and control to collect highly structured data that is analyzed using quantitative techniques.

Single-Subject Research

Despite its ability to yield precise answers and general conclusions, quantitative research is inherently limited in its capacity to generate novel or unexplored research questions. Furthermore, it is not well-suited for providing rich, detailed descriptions of specific groups' behaviors within particular contexts, nor does it effectively convey the subjective, lived experience of being a member of a given group.

Weaknesses of Quantitative Research

Qualitative and quantitative research differ significantly in their methodology and goals. Quantitative research generally starts with a focused hypothesis, gathering numerical data from large samples to draw general population conclusions using statistical techniques. In contrast, qualitative research begins with a broader, less focused research question and collects large amounts of unfiltered, nonnumerical data from a small number of individuals. Qualitative analysis relies on nonstatistical techniques to deeply understand the detailed experiences of participants rather than generating broad statistical generalizations.

Comparison of Qualitative and Quantitative Research

Survey research is a flexible methodology that incorporates both quantitative and qualitative approaches, defined by two primary characteristics. First, it relies on self-report measures, where researchers ask participants to directly report on their thoughts, feelings, and behaviors using tools like questionnaires or interviews. Second, it emphasizes rigorous sampling techniques, typically favoring large random samples to acquire accurate estimates of population characteristics. This makes survey research one of the few approaches in psychology that routinely relies on random sampling.

Characteristics of Survey Research

Which of the following statements best describes the methodology and primary objective of quantitative research in psychology?

Quantitative research is an empirical methodology wherein researchers start with a specific research question, collect numerical data from a sizable sample of participants, and analyze it using statistical techniques. As the most widely used approach in psychology, its primary objective is to deduce generalizable conclusions about a larger population.

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University of Michigan - Ann Arbor

University of Pittsburgh

There are two types of research methods: 

- Quantitative research
- Qualitative research

Both quantitative and qualitative types of research are required and often complement each other.  Science became more dependent on quantitative data and conduct quantitative tests and use qualitatively described relations.


Research methods in Data Science: Qualitative & Quantitative

The study design implemented by researchers for this study was: 
- Quantitative 
- Cross-Sectional  
- Analytical
- Retrospective 
- Non-experimental

MST & RE Type of Study 

Research methods are the techniques and strategies used while collecting or analyzing data.

Research Methods

The empirical method is a way of gaining knowledge based on observation and experimentation, rather than on logical argument or authority alone. Knowledge acquired through this method is considered empirical because it is grounded in objective, tangible evidence that can be consistently observed and verified by anyone. This focus on observable and repeatable evidence is a fundamental principle of scientific inquiry.

Empirical Method

H. Russell Bernard (March 2, 2012)

*Social Research Methods: Qualitative and Quantitative Approaches, Edition 2* 

Social Research Methods: Qualitative and Quantitative Approaches, Edition 2

Pearl, J., & Mackenzie, D. (2018). $\mathit{The \ Book \ of \ Why: \ The \ New \ Science \ of \ Cause \ and \ Effect.}$ Basic Books.

The Book of Why

https://kpu.pressbooks.pub/psychmethods4e/

KPU Research Methods in Psychology - 4th American Edition

Both data and analysis can be either qualitative or quantitative, meaning that there are four possible types of data and analysis combinations as follows: 

-  Quantitative analysis of quantitative data
-  Quantitative analysis of qualitative data
-  Qualitative analysis of quantitative data
-  Qualitative analysis of qualitative data

Four Possible Combinations of Qualitative-Quantitat ive Data and Analysis

Qualitative research is a methodological approach that originated in anthropology and sociology but is now widely applied in psychology. Rather than using numerical statistics to draw general population conclusions, qualitative researchers begin with a less focused research question to deeply understand the detailed experiences of their participants. They collect large amounts of unfiltered, nonnumerical data from a relatively small number of individuals and analyze it using techniques such as grounded theory, thematic analysis, critical discourse analysis, or interpretative phenomenological analysis.

Qualitative Research

Quantitative Research

https://online.stat.psu.edu/stat200/lesson/1/1.1/1.1.1

Categorical vs. Quantitative Data

Qualitative research in the field of food science strives to understand consumer behavior and motivation. Often, these methods are used to develop a hypothesis, which can be tested through quantitative research. Traditionally, qualitative methods can provide excellent insight to consumer behavior, but the data collected can be difficult to organize and interpret. Focus groups are the most common qualitative research tool applied to understand consumer behavior and identify possible areas of focus for product development.

The Use of Qualitative Research Methods in Data Science

 Cross-sectional design is one that evaluates or compares individuals, perhaps of different age groups, at the same point in time.

Cross-Sectional Approaches

UX research methods can be used to generate insights about users’ behaviors, motivations, attitudes, and needs. You can use different UX research methods to assess pain points and highlight opportunities to improve the user experience of a product.

UX Research Methods

The process of collecting information related to the research questions.

Data Collection Methods

The process of determining significance within collected information.

Data Analysis and Interpretation Methods

- Usually drawn from qualitative methods
  - Often adapted to utilize the strengths and perspectives of group members
- Indivdual roles may become group roles
  - Data Collection
- It is a dialogue 

Research Methods in Collaborative Groups

To understand, describe, and explain behavior and its underlying cognitive and biological processes, psychologists utilize a diverse range of research methods. These approaches span a spectrum from passive observational techniques to interactive methods involving direct engagement with study participants. The interactive methods themselves vary in complexity, from straightforward questioning in surveys and in-depth interviews to rigorously controlled experiments.

Research Methods in Psychology

A field study is a type of research conducted in a real-world, natural environment rather than an artificial laboratory. Because they take place in natural settings, field studies often exhibit higher external validity, allowing researchers to more effectively generalize their findings to the real world.

Field Study

The scientific process is driven by two inseparable forms of reasoning: deductive and inductive. While different research approaches may emphasize one over the other, both are essential components of the cycle of scientific inquiry. Deductive reasoning involves testing existing ideas against real-world evidence, whereas inductive reasoning uses real-world observations to generate new ideas.

The Types of Reasoning Within the Scientific Process

Facts are defined as observable realities. In the scientific community, facts are established exclusively through the collection of evidence from empirical research.

Fact

While we can sometimes determine the reason for a behavior by directly asking the individual, this approach is not always effective. People may be uncomfortable, unwilling to answer honestly, or completely incapable of responding (such as infants). In these situations, psychologists must employ creative methods to accurately understand the underlying causes of the observed behavior.

Need for Creative Methods in Studying Behavior

A researcher is investigating the claim that daily meditation reduces stress. Which of the following approaches for gathering knowledge is based on objective, tangible evidence that can be consistently observed and verified?

A life coach claims that their new motivational technique dramatically increases productivity, citing several powerful testimonials from clients who feel more successful. A researcher investigates the same technique by randomly assigning participants to either use the technique or a placebo activity, and then measures their output on a standardized task. Why is the researcher's method a more reliable way to gain knowledge about the technique's effectiveness?

Psychological science is considered an empirical field because its conclusions are founded on measurable data. This principle requires that phenomena under investigation must be quantifiable. For instance, while the internal state of an animal, such as a bird's happiness, cannot be directly measured, the internal states of humans can be assessed through methods like self-report, which provides a form of measurable data for scientific inquiry.

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