Study Guide for Course Final

Study Guide for Course Final

Describing Distributions with Numbers

The most common way to find the center of any data is to find the Mean.The mean is also known as the average or x, and can be found by adding up all the of data and dividing by the total number of data added together.

Another way to find the center of data is to find the Median.To find the median, first arrange all pieces of data in order from smallest to largest.The median is the middle of the data collected.If the median is two pieces of data, find the average of the two to determine the median.

The median does not change when an outlier is added, making it resistant, but the mean does change when an outlier is added, making it nonresistant to change. 

Describing Distributions with Numbers

There are six ways to measure spread:

Quartiles mark out the middle half of the data. The first quartile is 25% of the data, and the third quartile is 75% of the data collected.

Interquartile Range is the distance between the first quartile and third Quartile.

Outliers5 Number Summary are points that are 1.5 times the interquartile range.is the smallest piece of data, the first quartile, the median, the third quartile, and the biggest piece of data collected.

Box Plots are the five number summary in a type of graph.

Standard Deviation measures spread by looking how far far individual pieces of data is off from the mean.

About Quartiles

• Quartiles mark out the middle half of the data. The first quartile is 25% of the data, and the third quartile is 75% of the data collected.

  To find the quartiles, first arrange the data from smallest to largest and find the median.

  The first quartile (Q1) is the median of the data whose position in the list is to the left of the overall median.

  The third quartile (Q3) is the median of the data whose position in the list is to the right of the overall median. 

Describing Distributions with Numbers

The interquartile range is the distance between the first quartile and third quartile. 

The interquartile range is needed to find the outliers, which are are points that are 1.5 times the interquartile range.

The 5 number summary, consisting of the smallest value, the second quartile, the median, the third quartile and the largest value, leads to a new graph called a box plot.

Describing Distributions with Numbers

Standard Deviation measures spread by looking how far far individual pieces of data is off from the mean.

To find the standard deviation first find the mean of the set of data.Then subtract the mean from each individual piece of data and square the answer.

Last, add up all the new pieces of data and square root them.The answer from the square root you obtained is the standard deviation.

To find the variance, do all the steps above except square rooting the final answer.