1.1/1.2/1.3 AP STAT

Stemplot

Also called a stem-and-leaf plot. Data are separated into a stem and leaf by place value and organized in the form of a histogram.

Shape

The center is the median and/or mean of the data. The spread is the range of the data. And, the shape describes the type of graph. The four ways to describe shape are whether it is symmetric, how many peaks it has, if it is skewed to the left or right, and whether it is uniform.

Center

The center of a distribution is the middle of a distribution

The Median (M)

The midpoint of a distribution, the number such that half the observations are smaller and the other half are larger.

Symmetric

Being equal or the same in size, shape, and relative position

The 1.5 X IQR Rule for outliers

Call an observation an outlier if it falls more than 1.5 x IQR above the third quartile or below the first quartile

marginal distribution

Distribution of values of that variable among all individuals described by the table.

First Quartile (Q1)

If the observations in a data set are ordered from lowest to highest, the first quartile Q1 is the median of the observations whose position is to the left of the median.

Third Quartile (Q3)

If the observations in a data set are ordered from lowest to highest, the third quartile Q3 is the median of the observations whose position is to the right of the median.

Standard Deviation (Sx)

Measures the average distance of the observations from their mean. It is calculated by finding an average of the squared distances and then taking the square root.

Outliers

Numbers that are much greater or much less than the other numbers in the set

histogram

a bar graph depicting a frequency distribution

Dot Plot

a graphical device that summarizes data by the number of dots above each data value on the horizontal axis

Association

a group of people who have gathered based on similar goals or beliefs

Spread

a numerical summary of how tightly the values are clustered around the "center"

skewed distribution

a representation of scores that lack symmetry around their average value

Boxplot

displays the 5-number summary as a central box with whiskers that extend to the non-outlying data values

Uni/Bi/Multi-Modal

having or involving one mode. Bimodal is the practice of managing two separate but coherent styles of work. characterized by several different modes of activity or occurrence.

The Five Number Summary

minimum, 1st quartile, median, 3rd quartile, maximum

Variance

standard deviation squared

Interquartile Range (IQR)

the difference between the first and third quartiles

conditional distribution

the distribution of a variable restricting the who to consider only a smaller group of individuals

The Mean (X Bar)

the sum of the scores divided by the number of scores