Name: testing relationships in biology data
Uploaded: 2026-06-01T06:28:01.391Z
Duration: 1 min 27 s
Channel: JoVE

K12 Standards

ohios-learning-standards-and-model-curriculum

Ohio’s Learning Standards and Model Curriculum

9-12

Human Anatomy and Physiology

Levels Of Organization

Types of Tissues

Correlation and Causation

Results of an experiment may suggest that the independent and dependent variables are related.The relationship between variables, the correlation, can be positive, both variables increase or decrease together. Or negative, one increases and the other decreases.Additionally, there may be no relationship between the variables. To determine if an apparent correlation reflects a direct cause-and-effect association, a causal relationship, additional control experiments must be performed.For example, consider an ecosystem where geckos, parasitic ticks, and crows coexist. Crows prey on geckos, and ticks feed on animal blood.A researcher examines five different gecko populations and finds that the number of geckos without tails decreases as the number of parasitic ticks increases, showing a negative correlation.Based on this negative correlation alone, the researcher cannot tell whether the parasite directly causes tail loss.However, if the researcher had counted the number of crows at each location, he may have found a positive correlation between the number of crows and the number of tailless geckos.And after examining the crows&#x27; stomach contents, he would have also found the missing gecko tails.Together, these observations suggest that crows cause tail loss in geckos.But a correlation between two variables does not necessarily establish causation. A third variable may affect both variables, creating a correlation between them.

correlation and causation

<h3>Correlation and Causation</h3>Statistical tests can calculate whether there is a relationship, or correlation, between independent and dependent variables. A relationship between variables shows correlation, but it does not show cause-and-effect. A direct cause-and-effect relationship requires additional controlled experiments. If no consistent relationship exists between the variables, then there is no correlation.Correlation versus CausationIf the dependent variable increases or decreases when the independent variable increases, there is a positive or negative correlation, respectively, between the two variables. A correlation shows that variables change together, but it does not mean that one variable causes the other.For example, if a researcher wants to find the cause of tail loss in five different gecko populations and finds a negative relationship between the number of geckos without tails and the number of parasitic ticks, this result shows a negative correlation and suggests that the ticks may not be directly causing tail loss in geckos.However, if the number of crows near each gecko population is counted, a positive relationship between the number of crows and tailless geckos may be found. If, after examining the contents of the crows&#x27; stomachs, the missing gecko tails are discovered, the number of crows would directly affect the number of tails lost by the geckos&#x2014;showing causation. The earlier correlation could have been coincidental if the gecko tails had not been found in the crows&#x27; stomachs.Importantly, a positive or negative correlation does not mean that causation is present or absent. For example, time spent running and body fat show a negative correlation, and running can directly reduce body fat. On the other hand, ice cream sales and shark attacks show a strong positive correlation, but warmer weather increases both, not one another.In this example, there may also be a relationship between the number of crows and the number of parasitic ticks. The number of ticks may increase as the number of crows increases, showing a positive correlation. This may also lead to a positive correlation between ticks and tailless geckos. However, unlike the relationship between crows and tailless geckos, ticks and tail loss are not directly connected by cause and effect.

https://cloudfront.jove.com/files/ftp_upload/10652/10652_article_thumb_10652.jpg

Education

JoVE Core

Biology

Fundamentals

Scientific Inquiry

KEY TERMS AND CONCEPTS

testing relationships in biology data

Statistical tests can show whether two variables are related. This relationship is called a correlation. The variables may be independent and dependent, and the data may show a positive or negative pattern. If no consistent relationship appears, then there is no correlation.

A positive correlation means the dependent variable increases as the independent variable increases. A negative correlation means the dependent variable decreases as the independent variable increases. Correlation shows that variables change together, but it does not prove that one variable causes the other. A direct cause-and-effect link needs additional controlled experiments.

The gecko example shows why this matters. A researcher studying tail loss in five gecko populations might find a negative relationship between tailless geckos and parasitic ticks. That result shows correlation, but it does not prove that ticks cause tail loss. If the number of crows near each gecko population is counted, a positive relationship between crows and tailless geckos may appear.

Causation is only supported when the cause is directly linked to the effect. If gecko tails are found in the crows' stomachs, the number of crows directly affects the number of tails lost by the geckos. That means the earlier correlation may have been coincidental if the tails were not found. A correlation can look convincing without showing the real cause.

Some real-world examples also help show the difference. Time spent running and body fat have a negative correlation, and running can directly reduce body fat. Ice cream sales and shark attacks show a strong positive correlation, but warmer weather increases both instead of one causing the other. The number of crows and the number of parasitic ticks may also show a positive correlation, and ticks may then correlate with tailless geckos. Even so, ticks and tail loss are not directly connected by cause and effect.

Testing Relationships in Biology Data

the scientific method

Science Inquiry: Testing Ideas with Evidence

Science inquiry uses evidence to test ideas and refine them over time. Biologists and other scientists begin with observations made by the senses or by scientific tools. Those observations lead to a question and then to a hypothesis, which is a testable possible explanation. A good hypothesis must be falsifiable, which means it can be disproven if it is wrong. Scientists also think about the null hypothesis, which is the opposite idea being tested. In the slug and cabbage example, one...

inductive reasoning

Inductive Reasoning in Biology

Inductive reasoning in biology uses observations to build a general conclusion. It starts with related evidence and moves toward an idea that seems credible. Because the conclusion is not certain, inductive arguments can be strong or weak rather than valid or invalid. This kind of reasoning is common in descriptive science. A life scientist makes observations and records them. The data can be qualitative or quantitative. Scientists can also add drawings, pictures, photos, or videos to support...

deductive reasoning

Deductive Reasoning in Science Experiments

Deductive reasoning helps scientists turn a general idea into a specific test. It is the kind of logic used in hypothesis-based science, where researchers start with a rule or principle and predict what should happen next. This is the opposite direction from inductive reasoning, which begins with observations. With deductive reasoning, a scientist can make an if-then prediction from a hypothesis. For example, a researcher may hypothesize that butterflies are attracted to certain flowers...

Statistical tests can show whether two variables are related. This relationship is called a correlation. The variables may be independent and dependent, and the data may show a positive or negative pattern. If no consistent relationship appears, then there is no correlation. A positive correlation means the dependent variable increases as the independent variable increases. A negative correlation means the dependent variable decreases as the independent variable increases. Correlation shows...

key terms and concepts

Learn how correlation shows a relationship between variables, why it does not prove causation, and how gecko, running, and ice cream examples explain the difference.

Testing Relationships in Biology Data | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

biology

Virginia  Standards of Learning

HIgh School

BIO.1

BIO.1.a

Chemistry

CH.1

CH.1.a

Earth Science

ES.1

ES.1.b

Life Science

LS.1

LS.1.b

Texas Essential Knowledge and Skills

High School

Specialised Topic in Science

112.51.c.1.

112.51.c.1.A.

112.51.c.4.

112.51.c.4.A.

Florida Department of Education

Nature of Science

SC.912.N.1

SC.912.N.1.3

SC.912.N.1.6

BIO.4

BIO.4.B

Georgia Standards of Excellence

Epidemiology

SEPI3.

SEPI3.e

Overview of Anatomy and Physiology

Human anatomy is the scientific study of the body&#39;s structures. Some of these structures are very small and can only be observed and analyzed with the ...

structural-organization-of-the-human-body-an-overview

Structural Organization of the Human Body: An Overview

It is convenient to consider the body&#39;s structures in terms of fundamental levels of organization that increase in complexity: subatomic particles, ...

Functions of Life

Human life is characterized by a variety of functions that are essential for survival and well-being. These functions include metabolism, movement, ...

Characteristics of Life

Biology is a natural science that studies life and living organisms, including their structure, function, development, interactions, evolution, ...

https://cloudfront.jove.com/files/media/science-education/science-education-thumbs/10647.jpg

Levels of Organization

Biological organization is the classification of biological structures, ranging from atoms at the bottom of the hierarchy to the Earth&#x27;s biosphere. ...

Hierarchy of Organization

Content elaboration: Building on knowledge about cell structures and processes from middle school and Biology, this topic focuses on the increasing complexity of cells as they are organized into tissues. Several tissue types make up an organ. Several organs working together make up an organ system. All the organ systems interact and form the human body.

Hierarchy of Organization

Tissues

Tissues are a group of cells that share a common embryonic origin. Microscopic observation reveals that the cells in a tissue share morphological features ...

The Scientific Method

The scientific method is a detailed, empirical problem-solving process used by biologists and other scientists. This iterative approach involves ...

Inductive Reasoning

Inductive reasoning is a form of logical thinking that uses related observations to arrive at a general conclusion. It is uncertain and operates in ...

Deductive Reasoning

Deductive reasoning, or deduction, is the type of logic used in hypothesis-based science. In deductive reasoning, the pattern of thinking moves in the ...

Correlation and CausationStatistical tests can calculate whether there is a relationship, or correlation, between independent and dependent variables. A ...

Taxonomy

Taxonomy is the science of defining and naming groups of biological organisms based on shared characteristics. It uses a hierarchy of increasingly ...

Phylogeny

Phylogeny is concerned with the evolutionary diversification of organisms or groups of organisms. A group of organisms with a name is called a taxon ...

Types of Tissues

Content elaboration: The human body is comprised of four types of tissues: epithelial, connective, muscle and nervous. This topic includes a broad overview of the structure, function and location of each tissue type. Tissues can be studied as an independent unit or as they are encountered within each organ system. Investigations are used to understand and explain types of tissues in a variety of inquiry and design scenarios that can incorporate evolutionary concepts, scientific reasoning, comparative analysis, communication skills and real-world applications.

What is Homeostasis?

Maintaining homeostasis requires that the body continuously maintain its internal conditions. Each physiological condition has a particular set point, ...

Negative and Positive Feedback

Homeostatic Imbalance

Homeostasis is the maintenance of a stable internal environment within the body, which is crucial for the proper functioning of cells, tissues, organs, ...

pH Homeostasis

Acid-base homeostasis is essential for maintaining normal physiological activities in humans. The pH of various body fluids is strictly regulated because ...

Feedback Loops

In most cases, excessive hormone production is prevented by negative feedback&#8212;a loop that starts with a stimulus inducing the release of a ...

Hypothalamic-Pituitary Axis

The response to stress&mdash;be it physical or psychological, acute or chronic&mdash;involves activation of the Hypothalamic-Pituitary-Adrenal (HPA) axis. ...

Homeostasis

Content elaboration: Homeostasis is a theme that is explored throughout the course. Homeostasis involves positive and negative feedback mechanisms that continuously monitor and adjust the body's internal conditions (e.g., temperature regulation, pH, hormone regulation, blood pressure, hemostasis). At times, there can be a disruption (or disruptions) in the feedback loops, creating an imbalance. This homeostatic imbalance can result in a variety of conditions.

Homeostasis

Anatomical Terminology

Knowledge of anatomy is essential to understand human biology and medicine. Anatomists and health care professionals use standard terminology to describe ...

Anatomical Positions

In anatomy, several standard anatomical positions are used as references for describing the position and orientation of different body parts. These ...

Regional Terms

Regional terms describe anatomy by dividing the body parts into different regions that contain structures involved in contributing similar functions. ...

Directional Terms

Directional terms are essential for describing the relative locations of different body structures. For instance, an anatomist might describe one band of ...

Body Planes

Body planes in anatomy are imaginary flat surfaces used as reference points to divide the body into sections for anatomical study. These planes are ...

Anatomical Movements

Anatomical movements refer to the various actions or motions that can be performed by the body&#39;s joints and muscles. These movements are described ...

Abdominal Regions and Quadrants

To promote clear communication, for instance, about the location of a patient&#39;s abdominal pain or a suspicious mass, anatomists and clinicians ...

Anatomical Terminology

Content elaboration: Standard anatomical position is to be used as a reference point. Each area of the human body is identified by region. The features and structures of the body, relative to each other, are described by directional terms. The body and its organs can be divided by planes. The organs are located in cavities.

Testing Relationships in Biology Data

Description

Transcript

Tags

More videos by Standards