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

Erros no processo de medição são um problema comum. Tais erros podem se enquadrar em duas categorias: Aleatórios e Sistemáticos.
Erros aleatórios são o resultado de inconsistência no processo de medição ou variações na quantidade que está sendo medida. Isso resulta em flutuações, muito altas ou muito baixas, em torno do valor real.
Considere um cientista medindo o comprimento de uma minhoca usando um paquímetro. A inconsistência do cientista em ler as escalas corretamente, ou o movimento contínuo do corpo da minhoca durante a medição, pode resultar em medições incorretas do comprimento.
O erro aleatório não pode ser evitado, no entanto, pode ser calculado com tentativas repetidas.
Erros sistemáticos são os resultados de um problema persistente e levam a uma discrepância consistente na medição. Esses erros tendem a ser muito altos ou muito baixos em comparação com o valor real. Por exemplo, pesos sendo medidos usando uma balança calibrada incorretamente.
Estes são previsíveis e principalmente relacionados a instrumentos. No entanto, ao contrário do erro aleatório, não pode ser calculado com medições repetidas.

erros aleatórios e sistemáticos

Os cientistas sempre se esforçam ao máximo para registrar medições com máxima precisão e exatidão. No entanto, às vezes erros ocorrem. Esses erros podem ser aleatórios ou sistemáticos. Erros aleatórios são observados devido à inconsistência ou flutuação no processo de medição, ou variações na própria quantidade que está sendo medida. Esses erros podem ser maiores ou menores que o valor real em medições repetidas. Considere um cientista medindo o comprimento de uma minhoca usando uma régua. O erro aleatório nesse processo de medição pode ser resultado do método inconsistente com o qual o cientista lê as escalas, ou se a minhoca está se movendo. O erro aleatório não pode ser evitado; no entanto, ele pode ser compensado com repetidas tentativas.

Os erros sistemáticos surgem de um problema persistente e resultam em uma discrepância consistente na medição. Esses erros tendem a ser consistentemente maiores ou menores que o valor real. Eles são previsíveis e, em sua maioria, de natureza instrumental. Por exemplo, uma balança de pesagem mal calibrada pode consistentemente pesar objetos como se fossem mais pesados que seus valores reais. Ao contrário do erro aleatório, erros sistemáticos não podem ser compensados com medidas repetidas.

Este texto foi adaptado de <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>

Erros aleatórios e sistemáticos

Os cientistas sempre fazem o possível para registrar as medições com a máxima exatidão e precisão. No entanto, às vezes ocorrem erros. Esses erros podem ser ...

Education

JoVE Core

Physics

Física

Unit 1

Unidade 1

Units, Dimensions, and Measurements

Unidades, Dimensões e Medidas

KEY TERMS AND CONCEPTS

TERMOS-CHAVE E CONCEITOS

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...

orders of magnitude

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models, theories, and laws

Scientific Models, Theories, and Laws

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units and standards of measurement

SI Units for Physical Quantities

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base quantities and derived quantities

SI Base Units Behind Measured Quantities

SI base units are the starting point for measuring physical quantities. In any system of units, some quantities must be defined through direct measurement. These are called base quantities, and their units are base units. Other physical quantities are built from these base values by algebraic combinations. These are called derived quantities, and their units are derived units. For example, area comes from two lengths multiplied together. It is a derived quantity and is written in SI base units...

conversion of units

Unit Conversion Steps and Real-World Errors

Unit conversion lets you change a measurement from one unit to another. It is useful in everyday life, such as when a cookbook gives amounts in liters or ounces and you need cups instead. It also helps when directions use feet or meters, but you want to know the distance in miles. The first step is to list the given unit and the unit you need. The second step is to choose a conversion factor, which is a ratio that shows how many of one unit equal another unit. For example, 1,000 meters equal 1...

accuracy and precision

Repeated Measurements in Science

Repeated measurements help scientists check the quality of their results. They are used to judge both precision and accuracy. These two ideas are related, but they do not mean the same thing. Measurements are precise when repeated trials give very similar results. Precision shows how closely the values agree with one another. Measurements are accurate when the result is very close to the true value or the accepted value. Accuracy shows how closely the values agree with the real target. High...

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

Measurement precision depends on the tool used, and significant figures show that precision. A ruler can measure length to the closest millimeter. A caliper can measure length to the nearest 0.01 mm, so it gives a more precise measurement because it can detect very small changes in length. When a value is written from a measurement, the last digit is not exact. The person making the measurement must estimate that digit. For example, a stick that seems to fall between 13.2 cm and 13.3 cm must...

significant figures in calculations

Rounding Rules for Significant Figures

Rounding rules for significant figures help show the right level of certainty in measured results. When a calculation is reported with the correct number of significant figures, it better matches the uncertainty in the measurements. The rounding rule depends on the type of math being done. For addition and subtraction, the result should have the same number of decimal places as the number with the fewest decimal places. For multiplication and division, the result should have the same number of...

dimensional analysis

Dimensional Checks in Physics Equations

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problem solving: dimensional analysis

Dimensional Checks for Physics Equations

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solving problems in physics

Physics Problem Solving: Strategy to Check

Physics problem solving uses general physical principles to work out specific situations. It is a key skill in physics, and it can also help with everyday life. The same analytical skills can be used in new situations, while a list of facts can never cover every possible case. Solving physics problems also takes creativity and insight. These skills grow with experience and practice. There is no simple step-by-step method that works for every problem, but a three-stage process can guide the...

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

JoVE Core - Fisica apresenta a teoria e a aplicação de tópicos fundamentais da física, incluindo cinemática, dinâmica, mecânica dos fluidos, estática, ondas e acústica, com vídeos animados concisos e de fácil compreensão. Além disso, os vídeos de cientistas em ação demonstram a aplicação de conceitos relacionados em experimentos de pesquisa clássica e original realizados nos laboratórios de todo o mundo hoje em dia.

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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), 
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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.

Describe how scientific inferences are drawn from scientific observations and provide examples from the content being studied.

SC.912.N.1.6

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SC.912.N.1.7

How Measurement Errors Affect Results

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