Ch. 4 Flashcards
Summarizes the distribution of one variable by stacking dots at points on a number line that shows the values of the variable
A dot plot
Values on an ordered (minimum to maximum) data set that divide the data into four intervals
Quartiles
Values of an ordered data set that divide the data into 10 equal parts
Deciles
Values of an ordered data set that divide the data into 100 intervals
percentiles
The formula for finding location of a percentile
Lp = (n+1)P/100
What is an alternative to finding the quartiles using the exclusive method
The inclusive method
.25n + .75 for first quartile and .75n+.25 to find the 3rd quartile
A graphic display that shows the general shape of a variables distribution. It is based on five descriptive statistics: maximum, minimum, first and third quartiles and the median.
Box plot
The range of values between the first and third quartiles. 50% of the distributions values are located here
Interquartile range
A data point that is unusually far from the others. An accepted rule is to classify and observation as this if it is 1.5 times the interquartile range above the third quartile or below the first quartile
Outlier
What is the formula for an outlier
Upper boundary = Q3+1.5(Q3-Q1)
Lower boundary = Q1-1.5(Q3-Q1)
What are the four distribution shapes
- Symmetric
- Skewed to the right/Positively skewed
- Skewed to the left/negatively skewed
- Bimodal
What is the formula for Pearsons Coefficient of skewness
sk= 3(xbar-mediain)/s
Graphical technique used to show the relationship between two variables measured with interval or ratio scales
Scatter diagram
Used to measure the direction and strength between two variables. Can be any measurement between -1 and 1
Correlation coefficient
What does the visual correlation look like for -1, 0, and 1
-1 shows a strong negative relationship, 0 shows no relationship, and 1 shows a strong positive relationship
