Notes
Statistics and Dispersion Vocabulary and Notation
Getting started
We will be learning about the following terms in this unit:
1) Mean
2) Variance
4)
5) Mean absolute deviation
Z-score
3) Standard deviation
*The whole point of deviation is finding different ways of determining how far away the data
typically is from the ____________.
Mean of a data set
*The average of a data set is also called the _______________.
- The mean is represented by the symbol _____.
*We find the mean by finding the _______ of the data set and dividing by the number of
values.
- The number of values is represented by the symbol ______.
*A value in the data set is written as ____, where 𝑖 is that value’s place in the data set
(1st, 2nd, 3rd, etc.)
Variance
*Variance helps to tell us how spread out data values are from the mean.
*The variance is a number that subtracts each data value from the _______,
______________ each difference, then averages all of these differences together.
- Variance is represented by the symbol ____.
*The formula for variance uses the symbol ∑, which means _____, or ______.
Standard Deviation
*Standard deviation, like variance, is a number that tells us how spread out most data values
are from the ________.
- Standard deviation is represented by the symbol ____.
*In fact, standard deviation is just the __________ __________ of the variance.
*A small standard deviation means the data values are ________ together, while a large
standard deviation means the data values are ___________ apart.
Z-score
* A z-score refers to particular data points instead of the majority of points, like standard
deviation and variance.
* A z-score tells you how many ________________ ______________ a data point is
away from the mean.
*A positive z-score means the data point is larger than the __________, while a
negative z-score means the data point is ______________ the average.
Mean Absolute Deviation
*The mean absolute deviation is the average distance between each data value and the
_________.
*The mean absolute deviation is always ______________ since it uses absolute value.