How do you find inner quartile range?
Subtract Q1 from Q3
What two types of variables are included in a bivariate data set?
Explanatory and response variables.
What is the y variable?
The response variable.
What must be true about the shape of a symmetric distribution?
The distribution's mean is approximately equal to the median. (not that it's normal or unimodal)
What is the median?
Point that divides the measurement in half
How do you determine if a point is influential?
1. Run Regression
2. Remove point from data set
3. Rerun regression
4. If y-hat and r-sq changed significantly, then the point is influential
What are two commonly used measures to summarize the relation between two variables?
Scatter plots and Correlation coefficient
What is the x variable?
What is a joint frequency?
The frequency of two categories , one from each of the two classification criteria occur together.
What are the attributes of a histogram?
Contains intervals of values; measured in frequencies
When the distribution is skewed right, is the mean greater than or less than the median?
Mean is greater than the median
What does the correlation coefficient measure?
The strength and direction of a relationship.
What is a residual? How is it calculated?
The residual is the distance away the actual value is from the least-squares regression line. The residual is calculated by subtracting the predicted value from the actual value. (residual = actual - predicted)
What is marginal frequency?
The frequency that contains the total of a category.
Find the x-value of a data point at the 95th percentile in a distribution with a mean of 85 and standard deviation of 4.
x=91.56
What is a back to back stemplot?
Plot that can only be used to compare two data sets
Residual plots and coefficient of determination.
What 4 pieces of information can you extract from a regression output table?
explanatory variable
slope
y-intercept
r-sq
What is conditional relative frequency?
Frequency of one category given that the other category has occurred.
What is used to denote a population standard deviation?
Greek symbol sigma
Examine the tails and median.
What aspects of a linear regression are affected by either shifting or scaling? (hint: consider slope, y-intercept, r, and r-sq)
Y-intercept: shifting and scaling
slope: scaling
r: neither
r-sq: neither
How do you interpret r-sq?
R-sq is the percent of variation in the response variable that is account for by the linear model relating the response variable to the explanatory variable.
What aspects of univariate data is affected by shifting and scaling? (SOCS)
Spread (range, IQR, SD): scaling
Shape: neither
What is a z-score?
The number of standard deviations a value is away from the mean.