### Video Transcript

Which of the following statements
most correctly describes how zero measurement errors affect the accuracy and the
precision of measurements? A) Zero errors decrease both the
accuracy and the precision of measurements. B) Zero errors decrease measurement
precision. C) Zero errors do no affect
measurement accuracy or measurement precision. D) zero errors decrease measurement
accuracy.

Okay, so to answer this question,
we should first recall what the difference between accuracy and precision is. Simply put, the accuracy of a
measurement is how close a measured value is to its true value. In other words, a measurement is
accurate if the value that we measure is very close to the actual value of the
quantity we’re trying to measure. So, for example, after many, many
repeated measurements and many different experiments, we’ve gathered that the true
value of the gravitational field strength on earth is probably 9.8 meters per second
squared. However, if we were to do an
experiment now to try and measure this gravitational field strength and we got a
value of 25 meters per second squared, then we would say that this measurement is
not very accurate because it’s not close to the true value. So that’s accuracy.

Precision, on the other hand, is a
measure of whether repeated measurements under the same conditions will give the
same measured values. In other words, if we were to look
at our gravity measuring experiment again, where we were trying to find the
gravitational field strength on Earth. And the first experiment we did, we
found the value of 9.7 meters per second squared. And then, we repeated our
experiment under exactly the same conditions. So basically, we did everything
exactly the same way again. But this time, we got a value of 20
meters per second squared. And then, we did the experiment
again, doing everything exactly the same way as before. And then, we got a value of five
meters per second squared.

In this case, we would say that our
experiment is not precise because every time we repeat this experiment under the
same conditions, it’s giving us wildly different values. Now, this might be for various
reasons. We might be making a mistake in
terms of the experimental setup or the equipment that we’re using might be dodgy for
example. But the idea is that precision is a
measure of how close repeated measurements are to each other.

So now that we’ve looked at
accuracy and precision, we need to try and work out how zero measurement errors can
affect accuracy and precision. But first of all, what even is a
zero measurement error? Well, a zero measurement error is
simply a fault in our equipment that we’re using such that when the equipment should
read zero, it reads something else instead. For example, if we have a set of
weighing scales. So let’s say here is a set of
weighing scales. And when there’s nothing placed on
the weighing scales, that it reads zero kilograms.

Now, in this case, there is no zero
measurement error for this weighing scale because it is correctly reading zero
kilograms when it should read zero kilograms. There’s nothing placed on the
weighing scale. However, there would be a zero
measurement error if there was still nothing placed on the weighing scales. But the reading itself was not
zero. Let’s say the reading was two
kilograms. Well, in this case, everything that
we placed on the weighing scale, we will now think it’s two kilograms heavier than
it actually is. So, for example, let’s say that a
person who actually weighs 70 kilograms, steps onto the scales. In this case, due to the zero
measurement error, the scales will tell the person that they weigh 72 kilograms. And hence, the zero measurement
error is affecting the accuracy of the measurement because the measurement on the
scales 72 kilograms is not close to the true value of the person’s mass, which is 70
kilograms.

And so because of this, we can see
that zero measurement errors can affect the accuracy of measurements. However, zero measurement errors
will not affect the precision of measurements. And this is because the person
could step off the scales and then step back on the scales again. In other words, they’ll be
repeating their experiment where the experiment consists of them weighing
themselves. And they would be doing this under
exactly the same conditions as before. And the reading on the scales would
once again be 72 kilograms when they step back on the scales. So with repeated measurements, all
of the values that would be measured would be very close to each other. In other words, every time the
person steps on the scales, they would measure close to 72 kilograms. And so, the precision of the
experiment has not been affected. But as we’ve seen already, the
accuracy has.

And hence, out of options A to D,
we can rule out option A because this one says that zero errors decrease both the
accuracy and the precision which we’ve seen is not true. Option B can be ruled out too
because it says that zero errors decrease measurement precision, which is also not
true. And we can rule out Option C, which
says that zero errors do not affect measurement accuracy or measurement
precision. The answer that we’re looking for
is option D: zero errors decrease measurement accuracy.