Page 145: Interpreting Results

▫Shorter error bars = more precise data

▫Longer error bars = less precise data

▫If the error bars do notoverlap, the data
sets can be considered conclusively
different.

▫If the error bars overlap, there was not a
significant difference between the data
points, and therefore the different data
sets cannot be considered conclusively
different.

Averages

Error Bars

NOTES: Error Bars

To construct errors bars we use two measurements…

1.

Average of the data set

2.

Standard deviation

NOTES: Error Bars

●

Standard deviation gives a sense of how spread out the data is for
a give data set

●

It helps us see how varied the data is from the average

68% of data points within a data set fall within the standard deviation.

We will use a computer to calculate the standard deviation

NOTES: Standard Deviation

To calculate the TOP of an error bar…

AVERAGE + STANDARD DEVIATION

To calculate the BOTTOM of an error bar…

AVERAGE – STANDARD DEVIATION

Averages

Error Bars

NOTES: Error Bars

Sample 1

●AVG = 9.00

●SD = 3

Sample 2

●AVG = 11.00

●SD = 4