Categories: General

Quantitative method, Uses,Design and Components

QUANTITATIVE METHOD

EXPERIMENTAL DESIGN

Quantitative methods emphasize objective measurement and statistical, mathematical or numerical analysis of data collected through different polls and questionnaires, and surveys, or by manipulating pre-existing statistical data using computational techniques.

INTRODUCTION OF QUANTITATIVE METHOD

  • According to J.W.Best: “Experimental research is the description and analysis of what will be or what will occur, under the carefully controlled conditions”.
  • In experimental studies, the investigator tries to modify the situation to change the relationship between exposure and disease.
  • Studies with intervention are called experiments or clinical trials.
  • Experimental studies provide stronger pieces of evidence than observational studies.
  • Experiments are often artificial.
  • They are suitable for micro-level (small group phenomena).
  • They cannot directly answer the questions.
  • They involve animals or objects but most studies in medicine involve people.
  • Wilhelm M. Wundt (1832-1920): a German psychologist and physiologist, who introduced the experimental method into psychology.

OBJECTIVE OF QUANTITATIVE METHOD

  • Experiments are conducted to be able to predict phenomena.
  • To explain the causal relationship.

CHARACTERISTICS OF QUANTITATIVE METHOD

  • Manipulation
  • Control
  • Randomization

MANIPULATION:

It involves an intentional introduction, removal or change of the variable. We try to change the existing outcome or disease by making a change to exposure or a factor under study. The variable to be manipulated is the independent variable.

CONTROL:

The findings of experimental groups need to be compared with the controlled group. We can have either one control group or more than 1 control group. The minimum of one control group is needed in an experimental study.

RANDOMIZATION:

It is important because subjects have an equal chance to be placed in a control group or experimental group. It reduces the selection bias.

RANDOM ASSIGNMENT:

There should be a valid comparison. Compare apples to apples, don’t compare apples to oranges. It is not about fruit, it is about comparisons.

Why Assign Randomly

It is a way to divide the collection of participants into two or more groups to increase our confidence that the groups do not differ systematically. It is a mechanical method and it is automatic.

How to Randomly Assign

PARTS OF EXPERIMENT:

  • Independent variable
  • Dependent variable
  • Pretest
  • Posttest
  • Experimental group
  • Control group
  • Random assignment

PRETEST

An examination that measures the dependent variable of an experiment before the treatment.

POSTTEST

An examination that measures the dependent variable of an experiment after the treatment.

EXPERIMENTAL GROUP

The participants who receive the treatment in experimental research.

CONTROL GROUP

The participants who do not receive the treatment in experimental research.

You are familiar with other terms like random assignment, dependent variables, etc.

BLINDING

Blinding is a procedure in which one or more parties in a trial are kept unaware of which treatment was received. Blinding is an important aspect of any trial done to avoid and prevent conscious or unconscious bias in the design. Blinding is done to prevent bias.

EXPERIMENTAL DESIGN PROCESS OF QUANTITATIVE METHOD

CLINICAL TRIALS CATEGORIES

  1. CONTROLLED TRIALS
  2. CONCURRENT CONTROLS
  3. Randomized
  4. Not randomized
  5. SEQUENTIAL CONTROLS
  6. Self-controlled
  7. Crossover
  8. EXTERNAL CONTROLS
  9. STUDIES WITH NO CONTROLS

EXPLANATION OF ABOVE CLASSIFICATION

  1. CONTROLLED TRIALS
  2. CONCURRENT CONTROLS

  3. Randomized
  4. Not randomized: subjects are not randomized to treatment options. Studies that do not use randomized assignment are generally referred to as nonrandomized trials. These studies are open to so many sources of bias. These are weaker studies because of bias.

SEQUENTIAL CONTROLS:

  1. Self-controlled: the study of Sauter and colleagues involved patients who underwent cholecystectomy. Follow-up occurred 1 and 3 months after cholecystectomy to detect changes such as abdominal pain and flatulence. This type of study uses patients as their controls and is called a self-controlled study.
  2. Crossover: This study uses 2 groups of patients. One is experimental and the other is placebo or control. After a time, the experimental treatment and placebo are withdrawn from both groups for a washout period. During the washout period, patients receive no treatment. Then the first group now receives the placebo and the second group receives the experimental treatment. This design is called a crossover study.
  3. EXTERNAL CONTROLS: These are also called historical controls. This third method for controlling experiments is to use controls external to the study. The result of another investigator’s research is used as a comparison.

Types of experimental research

  • Pre-experimental design
  • True experimental design
  • Quasi-experimental design

1) PRE-EXPERIMENTAL DESIGN:

There are three types of pre-experimental study

  1. One-shot case-study design
  2. One-group pretest-posttest study design
  3. Static group comparison

Note: Examples are not mandatory, given here for better understanding.

ONE-SHOT CASE-STUDY DESIGN

This is also called the one-group posttest-only design. There is only one group, a treatment, and a posttest. There is no random assignment.

Example:

You take a group of forty newly hired wait staff and give all a 2-hour training session in which you instruct them to introduce themselves to customers by the first name and to check on the customers, asking, “Is everything fine?” 8 to 10 minutes after delivering the food (treatment). The participants begin employment, and you record the amount in tips for all for one month (posttest score).

ONE-GROUP PRETEST-POSTTEST STUDY DESIGN

There is one group, pretest, treatment, and posttest. It lacks a control group and random assignment. Measure the dependent variable before and after the treatment. It is an improved method.

Example:

You take a group of forty newly hired wait staff and give all a 2-hour training session. You instruct the staff members to follow a script in which they are not to introduce themselves by the first name and not to return during the meal to check on the customers. All begin employment, and you record the amount in tips for all for one month (pretest score). Next, you “retrain” all 40 participants and instruct them henceforth to introduce themselves to customers by the first name and to check on the customers, asking, “Is everything fine?” 8 to 10 minutes after delivering the food (treatment). Over the second month, you record the number of tips for both groups (posttest score).

STATIC GROUP COMPARISON

Also called the posttest-only nonequivalent group design. There are two groups, a posttest, and treatment. It lacks a random assignment and a pretest.

EXAMPLE

You give forty newly hired wait staff an identical 2-hour training session and instruct all to follow a script in which servers are not to introduce themselves by the first name and but to return during the meal to check on the customers. They can choose one of the two restaurants at which to work, as long as each restaurant has twenty people. All begin employment. After one month, you “retrain” the twenty participants at restaurant 1 (experimental group) and instruct them henceforth to introduce themselves to customers by the first name and to check on the customers, asking, “Is everything fine?” 8 to 10 minutes after delivering the food (treatment). The group at restaurant 2 (control group) is “retrained” to continue without an introduction or checking during the meal. Over the second month, you record the number of tips for both groups (posttest score).

3) QUASI EXPERIMENTAL STUDIES

Limited control over the independent variable. Explain the Causal relationship more certain than pre-experimental studies. Explain the causal relationships in situations in which classical design is difficult. Some have randomization but lack pretest.

Classification of quasi-experimental studies:

  1. PRE/POST STUDY DESIGN WITH/WITHOUT COMPARISON
  2. NON-EQUIVALENT CONTROL GROUP DESIGN
  3. Two group posttest only design
  4. Removed treatment design
  5. Repeated treatment design
  6. No treatment control group
  7. Cohort design
  8. CASE CONTROL STUDIES
  9. Interrupted time-series design
  10. Equivalent Time-series design
  11. Propensity Score Matching
  12. PRE/POST STUDY DESIGN WITH/WITHOUT COMPARISON

There is Pretest/posttest. It requires the collection of data on the study’s participants’ level of performance before the intervention took place (pre-) & then the collection of the same data after the intervention took place (post-). Allows making inferences on the effect of intervention by looking at the difference in the pre-test & post-test results.

With comparison (placebo is given to the control group)

Without comparison (placebo is not given to the control group)

  1. NON-EQUIVALENT CONTROL GROUP DESIGN
  2. TWO-GROUP POSTTEST-ONLY DESIGN:

Identical to the static group comparison. No pretest and random assignment in the static group. Here RANDOM ASSIGNMENT. It has all parts of the classical design except a pretest.

REMOVED TREATMENT DESIGN:

We can introduce treatment and also remove it. The dependent variable goes up after treatment. And it goes down when treatment is removed. This is evidence of the effect of treatment.

REPEATED TREATMENT DESIGN:

There are three parts i.e.; Pretest-treatment-posttest. When there is the removal of the treatment-posttest. There will be a change in the effect of treatment. When we restore the treatment-posttest, then again there will be a change in the effect of treatment.  In this way, we can check the effect of treatment.

NO TREATMENT CONTROL GROUP:

A comparison (control) group does not receive treatment. E.g., if a treatment group starts below the control Group & ends up above after treatment, a stronger influence of a treatment effect exists.

  1. COHORT DESIGN:

Group of people with similar characteristics within a defined period.

EXAMPLE:

THE EFFECT OF TOBACCO USE ON ADULTS WHO WORK FOR PAY.

This design can limit the confounding variables

This design is cheaper than RCT.

  1. CASE CONTROL STUDIES
  2. INTERRUPTED TIME SERIES:

No Control group, no randomization. A series of observations on a dependent variable over time. Interrupted by the introduction of an intervention. The time series should show an “effect” at the time of the interruption.

EQUIVALENT TIME SERIES:

An experimental plan with several repeated pretests, posttests, and treatments for one group often over some time. An equivalent time-series design is a one-group design similar to the interrupted time-series design. It extends over some time, but instead of a single treatment, the equivalent time-series design has the same treatment multiple times.

PROPENSITY SCORE MATCHING (PSM):

The propensity score is the probability of receiving treatment. This is a statistical matching technique. This is used for the effect of treatment and co-variables. It explains the causal relationship in observational studies. This is the estimation method.

ADVANTAGES

DISADVANTAGES

Most powerful design to establish a causal relationship between dependent and independent variables. Studies conducted in hospitals and communities, difficult to control extraneous variables.
Provides better results Several issues such as ethical reasons can hinder the experiment
Allow the researcher to have precise control over the variable. Participants can be influenced by the environment
Provides stronger evidence Time-consuming

SIGNIFICANCE

Experimental studies translate results of basic scientific research into better ways to prevent, diagnose or treat disease.

REFERENCES

Basic and Clinical Biostatistics by Beth Dawson and Robert G. Trapp

Pearson’s new International Edition, Social Research Method: Qualitative and Quantitative Approaches.

Introduction to statistical methods for clinical trials by Thomas D. Cook and David L. DeMets.

The concept of Blinding in clinical trials-EUPATI.

Recent Posts

First aid: Description, Importance and Principles

First aid  Definition First aid can be anything from putting on plaster to saving someone's life. The immediate care is… Read More

4 months ago

5 kg Healthy Weight Loss in One Month

Weight Loss Weight gain is a general problem nowadays. It affects daily life activities. The stubborn fats are not easy… Read More

4 months ago

Neonatal Intensive Care Unit: Role of Parents

Role of parents in the Neonatal Intensive Care Unit In most of the cases, the parents can stay with the… Read More

5 months ago

COVID-19: Preventive Measures for Corona Virus

Corona virus COVID-19 ,the respiratory illness corona virus has spread across the world and the WHO has officially declared the… Read More

5 months ago

Nutrition and Fluids in NICU

Nutrition and Fluids in the NICU Nutrition for babies in the Neonatal Intensive Care Unit The feeding process i.e. the… Read More

5 months ago

Detail overview of Neonatal Intensive Care Unit (NICU)

About the Neonatal Intensive Care Unit The Neonatal Intensive Care Unit (NICUs) has compound equipment, staff and devices for the… Read More

5 months ago

This website uses cookies.