Categorical Variable
places an individual into one of several groups or category
Quantitative Variable
numerical values for which it makes sense to find an average
Distribution
tells us what value a variable takes and how often it takes these values
Frequency Table
displays the counts or number of times a variable occurs
Relative Frequency Table
displays the percent of times a variable occurs
Symmetric
right and left sides of a graph are approximately mirror images
Skewed -
a graph having a long tail to the left or right
Mean
the average of the distribution
Median
the value in the middle of the distribution when data is ordered from least to greatest
Mode
the data which occurs the most in a distribution
Range
the difference between the highest and lowest value of a distribution
Interquartile Range
the distance between the 3rd and 1st quartiles
Outliers
Data that falls outside of the distribution and found by using the following: (IQR)1.5
Five Number Summary
consists of the smallest observation, the first quartile, the median, the third quartile and the largest observation
Standard Deviation
The average distance of the observations from their mean
Z-score
the standardized value that describes what fractional part of a standard deviation a value is from its mean
Empirical Rule
in a normal distribution it shows that 68-95-99.7 percent of the data is within 1,2 and 3 standard deviations
Percentile
a distribution of the values that fall a certain percent below this given value
Standard Normal Table
Table used to find the percent of data under the curve after converting a number into a z-score
Normal Probability Plot
a scatterplot of the z-scores against the explanatory variable that is used to suggest that the data is normal
Response Variable
the variable that measures the outcome of a study (y)
Explanatory Variable
the variable that may help explain or influence changes in a response variable (x)
Correlation r
measures the direction and strength of the linear relationship between two quantitative variables
Regression Line
a straight line that describes how a response variable y changes as an explanatory variable x changes
Extrapolation
The use of the regression line outside the range of the data from which it was calculated
Residual
The difference between the observed and the predicted values of y
Residual Plot
a scatterplot of the residuals against the explanatory variable used to determine if the regression line fits the data