Name: how measurement errors affect results
Uploaded: 2023-04-30T12:12:04.000Z
Duration: 1 min 20 s
Channel: JoVE

K12 Standards

Florida Department of Education

High School

Nature of Science

SC.912.N.1

SC.912.N.1.4

Random and Systematic Errors

Gli errori nel processo di misurazione sono un problema comune. Tali errori possono rientrare in due categorie: casuali e sistematici.
Gli errori casuali sono il risultato di un'incoerenza nel processo di misurazione o di variazioni nella quantità misurata. Questi si traducono in fluttuazioni, troppo alte o troppo basse, intorno al valore reale.
Considera uno scienziato che misura la lunghezza di un lombrico usando un calibro. L'incoerenza dello scienziato nel leggere correttamente le squame, o il movimento continuo del corpo del lombrico durante la misurazione, possono portare a misurazioni errate della lunghezza.
L'errore casuale non può essere evitato, tuttavia, può essere mediato con prove ripetute.
Gli errori sistematici sono il risultato di un problema persistente e portano a una discrepanza costante nella misurazione. Questi errori tendono ad essere troppo alti o troppo bassi rispetto al valore reale. Ad esempio, i pesi vengono misurati utilizzando una bilancia tarata in modo errato.
Questi sono prevedibili e per lo più legati allo strumento. Tuttavia, a differenza dell'errore casuale, non può essere mediato con misurazioni ripetute.

errori sistematici e causali

Gli scienziati hanno sempre fatto del loro meglio per registrare le misurazioni con la massima accuratezza e precisione. Tuttavia, a volte si verificano degli errori. Questi errori possono essere casuali o sistematici. Gli errori causali sono osservati a causa dell'incoerenza o della fluttuazione nel processo di misurazione, o delle variazioni nella quantità stessa che viene misurata. Tali errori fluttuano dall'essere maggiori o minori del valore reale nelle misurazioni ripetute. Consideriamo uno scienziato che misura la lunghezza di un lombrico usando un righello. L'errore causale in questo processo di misurazione potrebbe essere il risultato del metodo incoerente con cui lo scienziato legge le scale, o se il verme si sta muovendo. L'errore casuale non può essere evitato; tuttavia, esso può essere tenuto nella media effettuando misurazioni ripetute.

L'errore sistematico deriva da un problema persistente e comporta una consistente discrepanza nelle misurazioni. Questi errori tendono ad essere sia consistentemente maggiori che minori del valore reale. Possono essere previsti e sono maggiormente di natura strumentale. Per esempio, una calibrazione impropria di una bilancia potrebbe portare ad attribuire agli oggetti un peso maggiore di quello avuto in realtà. Diversamente dall'errore causale, gli errori sistematici non possono essere tenuti nella media attraverso misurazioni ripetute.

Questo testo è adattato da <a href="https://openstax.org/books/chemistry-2e/pages/1-5-measurement-uncertainty-accuracy-and-precision">Openstax, Chemistry 2e, Section 1.5: Measurement Uncertainty, Accuracy, and Precision.</a>

Errori sistematici e causali

Gli scienziati fanno sempre del loro meglio per registrare le misurazioni con la massima accuratezza e precisione. Tuttavia, a volte si verificano errori. Questi errori possono essere ...

Education

Didattica

JoVE Core

Physics

Fisica

Unit 1

Unità 1

Units, Dimensions, and Measurements

Unità, dimensioni e misurazioni

KEY TERMS AND CONCEPTS

TERMINI E CONCETTI CHIAVE

how measurement errors affect results

Measurement errors can change how accurate and precise a result appears. Scientists try to record measurements as carefully as possible, but errors can still happen. These errors are usually random or systematic.

Random errors come from inconsistency or fluctuation in the measuring process. They can also come from changes in the quantity being measured. In repeated measurements, random error may make a value appear greater than the true value one time and less than it the next.

A simple example is measuring the length of an earthworm with a ruler. The error could come from reading the scale differently each time. It could also happen if the earthworm moves during the measurement. Random error cannot be avoided, but repeated trials can help average it out.

Systematic errors come from a persistent problem that causes a steady measurement shift. They usually make results consistently greater than the true value or consistently less than it. These errors are predictable and are often instrumental in nature.

An improperly calibrated weighing balance is one example of systematic error. It may keep weighing objects heavier than they really are. Unlike random error, systematic error cannot be averaged out by repeating the measurement.

How Measurement Errors Affect Results

the scope of physics

How Physics Shapes Science and Technology

Physics studies the interactions of energy, matter, space, and time. It looks for the basic mechanisms that explain natural phenomena. The word physics comes from the Greek word physis, which means nature. Physics helps us understand the natural world at its most fundamental level. It relies on quantitative laws, or rules written in numbers and measurements, to describe how things behave. That approach can also help other fields improve the limits of current technology. Physics matters in...

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units and standards of measurement

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base quantities and derived quantities

SI Base Units Behind Measured Quantities

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Unit Conversion Steps and Real-World Errors

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accuracy and precision

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random and systematic errors

Measurement errors can change how accurate and precise a result appears. Scientists try to record measurements as carefully as possible, but errors can still happen. These errors are usually random or systematic. Random errors come from inconsistency or fluctuation in the measuring process. They can also come from changes in the quantity being measured. In repeated measurements, random error may make a value appear greater than the true value one time and less than it the next. A simple...

rules for significant figures

Measurement Precision and Significant Figures

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significant figures in calculations

Rounding Rules for Significant Figures

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dimensional analysis

Dimensional Checks in Physics Equations

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key terms and concepts

Learn how random and systematic errors affect scientific measurements, with clear examples like a moving earthworm and an uncalibrated balance.

How Measurement Errors Affect Results | JoVE K12

physics

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Define a problem based on a specific  body of knowledge, for example: biology, chemistry, physics, and earth/space science, and do the following:  
Pose questions about the natural world, (Articulate the purpose of the investigation and identify the relevant scientific concepts). 
Conduct systematic observations, (Write procedures that are clear and replicable. Identify observables and examine relationships between test (independent) variable and outcome (dependent) variable. Employ appropriate methods for accurate and consistent observations; conduct and record measurements at appropriate levels of precision. Follow safety guidelines). 
Examine books and other sources of information to see what is already known, 
Review what is known in light of empirical evidence, (Examine whether available empirical evidence can be interpreted in terms of existing knowledge and models, and if not, modify or develop new models). 
Plan investigations, (Design and evaluate a scientific investigation). 
Use tools to gather, analyze, and interpret data (this includes the use of measurement in metric and other systems, and also the generation and interpretation of graphical representations of data, including data tables and graphs), (Collect data or evidence in an organized way. Properly use instruments, equipment, and materials (e.g., scales, probeware, meter sticks, microscopes, computers) including set-up, calibration, technique, maintenance, and storage). 
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Generate explanations that explicate or describe natural phenomena (inferences), 
Use appropriate evidence and reasoning to justify these explanations to others, 
Communicate results of scientific investigations, and 
Evaluate the merits of the explanations produced by others.

SC.912.N.1.1

Describe and explain what characterizes science and its methods.

SC.912.N.1.2

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SC.912.N.1.3

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SC.912.N.1.5.

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SC.912.N.1.6

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SC.912.N.1.7

How Measurement Errors Affect Results

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