Set up page 25 as follows: Name 9/4/15 Class Notes: Accuracy and Precision EQ: How are measurements determined to be accurate or precise?

Accuracy Measurement of how close a measurement comes to the actual or true value Think of accuracy like hitting the bullseye on a target.

Precision Can you reproduce the data Need more than one measurement Think of this like hitting the same area of a target more than once.

Three targets with three arrows each to shoot. Can you hit the bull's-eye? Both accurate and precise Precise but not accurate Neither accurate nor precise How do they compare? Can you define accuracy vs. precision?

Accuracy and Precision Accurate and Precise x xx

Accuracy and Precision Not Accurate but they are precise x x x

Accuracy and Precision Accurate but Not Precise x xx

Accuracy and Precision Not Accurate and Not Precise x x x

Precision of Lab Equipment Precision refers to the reproducibility of data The more precise a piece of equipment, the more likely you are to get the same measurement repeatedly.

Precision of Lab Equipment When you look at a piece of equipment, first look at its graduations (markings) and try to find out what the lines mean. The more precise piece of equipment has the smallest increment change between the markings Usually the piece of equipment with the more graduations (lines) is the more precise.

Precision of Lab Equipment Increment = 1 mL Increment = 0.2 mL More Precise

a) or More graduations – your measurements will be more precise

b) or More graduations – your measurements will be more precise

c) or More graduations – your measurements will be more precise

d) or More graduations – your measurements will be more precise

Set up page 24 as follows: Name 9/4/15 Precision of Lab Equipment Activity EQ: Can I identify the piece of lab equipment that is more precise?