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This video is about systematic and random errors.

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We will discuss errors during measurement, systematic errors, and random errors.

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When we measure something not only in physics, but anywhere else in life,

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we never get an exactly accurate and precise result.

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In other words, our measurement will always be at least a bit off.

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This is caused by measurement errors, which in turn lead to uncertainties in our measurement data.

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Two examples are measuring the mess of an object on a scale,

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and measuring the time it takes for a ball to roll down a slope.

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Errors in the mess might be the result of an uncalybreaded scale,

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while the time we measure for a ball to roll down a slope,

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is usually affected by our reaction time.

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There are two types of errors we consider in physics.

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Systematic errors and random errors.

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Let's start by discussing systematic errors.

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Systematic errors, as the name suggests, are caused by the system that we use to make measurement.

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These errors are very often due to faulty equipment.

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An example is a so-called zero error on a scale.

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This is high zero error looks like on an analog scale.

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Before using this scale to measure something,

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the pointer, the arrow, should be pointing at zero.

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As you can see, the pointer on this scale is below zero.

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This will cause all measurements to be smaller than the actual value.

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In other words, a systematic error results in the same constant error for all measurement values.

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If you have done science experiments, in some of them you have probably carried out repeated readings,

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or trials, and then found the average or mean of these results.

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An important point to remember here is that repeated readings or trials do not remove systematic errors.

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This makes sense because if every reading or trial has the same error,

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then their average will also have the same error.

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The only way to remove or minimize systematic errors is to check your equipment

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and verify that it's working properly.

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Finally, you have probably heard a term accurate when describing measurements.

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When a measurement is accurate, it means that it has small systematic errors.

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It might be a good idea to add this word to your physics vocabulary.

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Next, let's discuss random errors.

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These are errors that are caused by environmental or procedural limitations.

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An example is small changes in posture when measuring the height of someone.

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Let's assume that the actual height of a person is 181.3 cm.

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We measure the height of this person on four different days in a row and get the following values.

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Two of these values are smaller than two are larger than the actual value.

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So random error means that the results are clustered around the same value,

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some larger and some smaller than the actual value.

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In order to avoid or minimize random errors, we can take repeated readings or trials

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and then calculate the average or mean of these results.

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You have most likely done this in previous science experiments.

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And finally, a word for your physics vocabulary,

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measurements with small random errors are said to be precise.

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Let's summarize what we have covered.

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We have seen that measurements always have errors,

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sometimes small, sometimes large, which lead to uncertainties in the data that we collected.

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We discussed systematic errors, which are caused by the measurement system that we use,

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and this is very often faulty equipment.

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Systematic errors result in the same constant error in all measurement values,

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and these errors are not removed by repeated readings or trials.

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They can only be minimized by checking and verifying equipment.

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Measurements that have small systematic errors are said to be accurate.

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We also covered random errors, which are due to environmental or procedural limitations.

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In other words, these errors occur not because of the equipment,

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but often because of how we use the equipment.

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Random errors cause results that are clustered around the same value,

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and can be minimized by taking repeated readings or trials and calculating the mean.

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You have almost surely done this in previous science experiments.

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Finally, measurements with small random errors are said to be precise.

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This completes our discussion of systematic and random errors.

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In the next video, we will learn how to record and work with uncertainties.