Data Analysis Mean, Median, Mode and

Box and Whisker

Put data in order very first!!!!!!

Mean

• Add all of the numbers together in the set and divide by how many numbers there are. Round to the nearest tenth only when necessary.

Median

• The median is the middle number of the set after the data is in numerical order.

• If there is an odd number of numbers in the set then there will be an exact middle.

• If there is an even number of numbers in the set then there will not be an exact middle and you need to take the two middle numbers and add them together and divide by 2.

Mode

• This is the number or numbers that occur most often. (not the highest number)

• If all of the numbers occur the same amount of times there is no mode, not zero.

Minimum Value

• The very smallest number in the original set of data.

Maximum Value

• The largest number in the original set of data.

Range

• Subtract the maximum (highest number in the set of data) and the minimum (smallest number in the set of data)

Lower Quartile

• The median divides the data in half. The lower quartile is the median of the lower half of the data.

• Again, if there are two numbers in the middle of the lower half of data, add them together and divide by 2.

• Don’t include the actual median in either side of the data.

Upper Quartile

• This is the middle of the upper half of data after finding the actual median.

• Again, if there are two numbers in the middle add them together and divide by 2.

• Again, don’t include the actual median in either side of the data.

Interquartile Range

• Subtract the upper quartile and the lower quartile

Directions for making a Box and Whisker Plot

1. Arrange the data in order from least to greatest. (You should have already done this!!)

2. – 5.Draw a number line that will include all data. Make sure to evenly space the intervals

between numbers. (Ex. Go by 2’s, 3’s, 4’s, 5’s, 10’s, etc.)

6. Make dots above or below the line at:1. Median

2. Minimum Value3. Maximum Value4. Lower Quartile5. Upper Quartile

7. Draw a box from the lower to the upper quartile. Make sure outside of box goes through the dots on each end.

8. Draw a line through the box at the median from the top of the box to the bottom of the box.

9. Draw lines from the minimum to the lower quartile.Draw a line from the maximum to the upper quartile.

These are the whiskers ** Sometimes you will only have one whisker or maybe no whiskers. This will occur if your lower quartile and

your minimum are the same or the upper quartile and the maximum are the same.