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3. Measurement in Science
In science, we want measurements
to be both accurate and precise.
What is the difference between
accurate and precise?

6. The difference between the two
• Accuracy refers to how closely a
measured value agrees with the correct
value.
• Precision refers to how closely
individual measurements agree with
each other.

7. Accurate, Precise, or Both?

8. Accurate, Precise, or Both?

9. Accurate, Precise, or Both?

10. Percent Error
Someone give me the percent error formula we used yesterday...
Percent error = ([experimental value -accepted value]/accepted value) * 100%
That absolute value meams that P.E. is always positive and also it doesn't matter whether you start with experimental value or accepted value.

11. Mean, Median & Mode
Don't want to bore you, but gotta cover my bases:
Mean - average: add totals of data together and divide by the number of values present in data.
Median - Number in data that sits in the middle of the whole set of data points
Mode - Number in set of data that occurs most often

12. Range vs. Spread
The range of data is the subtraction from the outliers...What does this mean?
Calculate the range of this set of data:
62, 180, 54, 60, 98, 125, 75, 97, 86.
Range is 120: Subtraction of the outliers 180 and 60.

13. Spread
The spread is the average of how much each separate data point varies from the average or mean. In this class, we will call this the Standard Deviation.
To find the S.D., use this formula:

14. Kinda scary...so we'll simplify it.
Take all the original numbers and subtract each one individually from the average. Square that answer. This is your total for that individual number. Add up all your samples, then divide it by the total number of samples. once you have done that you take the square root of these numbers, and you have your S.D.

15. Add all those together and divide by the total number of values = 8.
Consider this set of data of the following eight values:
2, 4, 4, 4, 5, 5, 7, 9: calculate the average
Avg. = 5, so we subtract 5 from each one of these values and square it.
Add all those together and divide by the total number of values = 8.
Take the square root of that, which gives you your Standard Deviation.