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## AP®︎/College Statistics

### Course: AP®︎/College Statistics>Unit 2

Lesson 3: Describing the distribution of a quantitative variable

# Clusters, gaps, peaks & outliers

Examples looking at different features of distributions, such as clusters, gaps, peaks, and outliers for distributions.

## Want to join the conversation?

• What is an outlier?
What is a range?
What is an interquartile range?
What is mean?
What is median?
What is mode?
What is a lower quartile?
What is an upper quartile?

I have them all mixed and am so confused.
• Outlier - a data value that is way different from the other data.
Range - the Highest number minus the lowest number
Interquarticel range - Q3 minus Q1
Mean- the average of the data (add up all the numbers then divide it by the total number of values that you originally added)
Median - the number in the middle of the data. If the numbers are all in order, whichever number is in the middle
Mode - whichever number there is the most of
Lower Quartile - Q1 - the middle of the bottom half of the data, if you take the median, it's the middle of the data on the right of the median(it's basically the number at the 1st quarter.
Upper Quartile - Q3 - the middle of the data above the median, the value at the 3rd quarter of the data.
• What is the exact meaning of an outlier?
• 1) A data point that is distinctly separate from the rest of the data.
2) Any data point more than 1.5 interquartile ranges (IQRs) below the first quartile or above the third quartile.

www.mathwords.com/o/outlier.htm
• Using the last example in the video, what if there are
20 students with a score of 0-1,
2 students with a score of 8-9,
3 students with a score of 10-11,
1 student with a score of 12-13,
5 students with a score of 14-15,
2 students with a score of 16-17 and,
2 students with a score of 18-20.

Is there an outlier, what can we tell from this data?
• yes, If you plot these they are pretty close together. Except for The 1st, that is way out there. Another example of an outlier based on this data would be 1 student with a score of 30-31. That would be an outlier.
• Can you please explain peak?
• a peak, like he said in the video is the hight of the numbers. or the highest point.
• What is cluster? explain please.
• It is data is is clustered like 2 or 3 groups together like if it was 4 - 9 and 6-8 had 3 dots then the cluster would be 6-9
(1 vote)
• Whats a outlier
• An outlier is a piece of data that is far away from other data.
• What's a spread
• In statistics this is a measure of the variation of the data. For example, the range (difference between maximum and minimum values), the mean absolute deviation (average distance between each point and the median), and interquartile range (distance between the lower and upper quartiles).
• outlier is a small set of data separated from all the big clusters? Right?
• It's usually only one data point (I think)
• a few questions about outlier

1.lets say there is are two clusters on the graph with a huge gap in between
would data in one cluster be considered as an outlier wrt another cluster ? or does this not have any outlier at all

2.lets say that this time there is a cluster on one side of the graph . but after the cluster the data points are just low but no gaps . but after a while for one value there is an abnormally high no.of data points
is this consider an outlier ?
(shown below)
.________.____
..._______.____
..._______.____
.......................__

. -> data point
-> space/blank (the comment isnt taking more than one space when given , thats why i used underscore)