Do you include outliers in a box plot?
Box plots are useful as they show outliers within a data set. An outlier is an observation that is numerically distant from the rest of the data. When reviewing a box plot, an outlier is defined as a data point that is located outside the whiskers of the box plot.
How does SPSS define outliers in Boxplots?
SPSS uses Tukey’s method to identify outliers, which are visible on boxplots. Finding outliers using that method can be thought of as a rule of thumb, not a statistical rule set in stone. While there are more advanced methods for finding outliers, like Grubb’s Test, SPSS doesn’t offer them.
How can you use Boxplots to detect outliers?
In the boxplot below, the length of the box is IQR, and the minimum and maximum values are represented by the whiskers. The whiskers are generally extended into 1.5*IQR distance on either side of the box. Therefore, all data points outside these 1.5*IQR values are flagged as outliers.
Do you include outliers in 5 number summary?
The five numbers are the minimum, the first quartile(Q1) value, the median, the third quartile(Q3) value, and the maximum. The first thing you might notice about this data set is the number 27. This is very different from the rest of the data. It is an outlier and must be removed.
How does SPSS define extreme outliers?
SPSS also considers any data value to be an extreme outlier if it lies outside of the following ranges: 3rd quartile + 3*interquartile range. 1st quartile – 3*interquartile range.
How does SPSS define outliers?
Summary. Outliers are basically values that fall outside of a normal range for some variable.
What do SPSS Boxplots show?
In a boxplot, the width of the box does not mean anything (usually). The thick line in the middle is the median. The top and bottom box lines show the first and third quartiles. The whiskers show the maximum and minimum values, with the exceptions of outliers (circles) and extremes (asterisks).
Does maximum include outliers?
The minimum and maximum values can also be the outliers. An outlier is a value that is much larger or smaller than the other values in a data set, or a value that lies outside the given data set. Remember that an outlier will always be the minimum and/or maximum values.