Technical errors can be divided into two categories: accidental errors and systematic errors. As the name suggests, random errors occur at regular intervals, with no apparent motive. Systematic errors occur when there is a problem with the instrument. For example, a scale could be poorly calibrated and read 0.5 g with nothing on it. All measures would therefore be overestimated by 0.5 g. If you don`t take this into account to your extent, your measurement contains a few errors. The reproducibility of a measurement is called accuracy. If all the measures are very similar, we say that the determined value is well known. If we cannot get very similar measures, we cannot say that the value is well known, but we say that the measures are imprecise.
A number of measurements can be described as accurate when the area is very small, i.e. the area near 0 A is described as imprecise when the area is wide, i.e. the range is not close to 0. The reproducibility of a measurement is called accuracy. If all the measurements are very similar, we say that the determined value is known. If we cannot get similar measures, we cannot say that the value is known, but we say that the measurements are imprecise. A set value is accurate if the percentage of relative error is low, close to 0%. The percentage of the relative error in the student`s results is NOT close to 0%.
The student`s temperature values are NOT accurate, they are imprecise. If balance 1. is used, we can record the value of 7.90 g with a relative error percentage of 0.00%. If balance 2 is used, we can record our value of 5.78 g with a relative error percentage of 26.8%. For example, the iron cube has a real value of 7.90 ± 0.01 g the actual value is between 7.90 – 0.01 – 7.89 g and 7.90 – 0.01 – 7.90 g. A precise value for the mass of iron would be between 7.89 g and 7.91 g. An inaccurate value for the mass of iron would be less than 7.89 g or greater than 7.91 g. As it is very rare for chemists to know exactly how a measurement is a measure, they make a series of measurements under the same conditions, until they arrive at a series of measurements that fit perfectly. (1) If we know the tolerance of a real measure, we can decide that the determined value is accurate if it falls within the tolerance levels of the true measure and imprecise if it is outside the tolerance levels of the actual value. The range of values – highest value – lowest value – 23.91 – 23.24 – 0.67 The range of values is closer to 1 than to 0, so we would decide that the student`s measurements are NOT accurate, they are imprecise.
If you perform a series of replication tests (i.e. identical in all respects), you will probably get scattered results. The actual value of the volume of water in the bottle is 50.00 ± 0.06 ml. This means that the actual value of the volume of water in the stolen bottle could reach 50.00 – 0.06 – 49.94 ml or up to 50.00 – 0.06 – 50.06 ml. For the student`s measurements to be considered accurate, the value obtained must be between 49.94 ml and 50.06 ml. The determined value is the average measure of the volume the student records with 49.89 ml. The value of the student is less than the lowest real value for a given measure. For example, as we know, the real value of the mass of an iron cube is 7.90 g. They weigh the same cube of iron and find that it has a mass of 7.90 g. The actual value and value are the same, so we can say that we have accurately determined the mass of the iron cube.
A set of measurements is accurate when all measurements are very similar, i.e. when there is a small range of values. Accuracy is the proximity of a measure to fair value for this measurement. The accuracy of a measurement system refers to the proximity of the concordance between repeated measurements (repeated under the same conditions).