# Difference Between Accuracy And Precision Lab Report

10.23.2016

IBC 1

Question

What is the difference between accuracy and precision and how can we demonstrate the difference?

MATERIALS

Pencil

Notebook Paper

100 mL Graduated Cylinder

1 Gallon of water

Ruler

Unmarked Plastic Container

3 different kinds of Rocks of different sizes

Triple Beam Balance

PROCEDURE

Estimating Lengths Procedure

A piece of notebook paper was torn into 8 rectangles

Without a ruler, a line was drawn which was estimated to be 5cm long on one of the rectangles

Repeated step 2 on three separate sheets of paper

Measured the length of the lines with a ruler

Repeat the above process with the remaining 4 pieces

Measure the actual lengths of the lines drawn with

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Accuracy is represented by percent error. The lower the percent error the more accurate the measurement is. For Example a low percent error of 4% is accurate vs 100%. Precision is when the estimated value is not as close to the actual value, but all of the estimated values are close to each other. Precision is represented by Average Deviation. The lower the average deviation is the more precise a measurement. For example 1.1 and 1.2 is precise because they are close to each other.

EVIDENCE:

The percent error for the hand drawn lines table 1 data was precise because the average deviation was 0.625. As for data table 2 data was precise because its average deviation was 0.75. Neither data sets were accurate because the percent error for both was greater than 10%.

The second data set which measured volume was neither precise nor accurate because the percent error was greater than 10% (21%). The average Deviation was 19.75 which is not precise.

The third data set which measured mass was neither precise nor accurate because the percent error was greater than 10%(67%) The average deviation was 5.6 which is not

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This may have caused the measurements to be off.

My ideas haven't changed because i've done this lab before. For future experience i have to look at the broader picture like “what will happen if this isn’t done right”. I now have an understanding on accuracy and precision on how they relate to percent error and average deviation.

LAB QUESTIONS:

Questions Hand Drawn lines

Data set 2 because the percent error was lower than Data set 1.

Data set 2 because the deviation was less than data set 1.

In this case yes but it does not have to be because of the average deviation.

Questions Estimating Volume

No because the percent error as long as it’s above 10% it’s not accurate.

Yes because I got a feel of how much to fill the unmarked plastic container

Yes because I got a feel of how much to fill the unmarked plastic container.

Questions Estimated Mass

No because the percent error as long as it’s above 10% it’s not accurate.

No because I had different masses with different trials because we had different rocks which had different masses.

No because each trial was different.

Length because I got a feel for it as we kept going through