What are whiskers in Minitab?

The whiskers represent the ranges for the bottom 25% and the top 25% of the data values, excluding outliers. Hold the pointer over the boxplot to display a tooltip that shows these statistics. For example, a boxplot may show that the median length of wood boards is much lower than the target length of 8 feet.

How do you do a box-and-whisker plot in Minitab?

How to Use Minitab to Generate a Box Plot

1. Click Graph → Boxplot.
2. A new window named “Boxplots” pops up.
3. Click “OK” in the window “Boxplots.”
4. Another new window named “Boxplot– One Y, Simple” pops up.
5. Select “HtBk” as the “Graph Variables.”
6. Click the “Data View” button and a new window named “Boxplot– Data View” pops up.

What do the whiskers on a box plot mean?

Whiskers. The upper and lower whiskers represent scores outside the middle 50% (i.e. the lower 25% of scores and the upper 25% of scores). The Interquartile Range (or IQR) This is the box plot showing the middle 50% of scores (i.e., the range between the 25th and 75th percentile).

Why does my Boxplot have no whiskers?

For a box-and-whisker plot you order the data numerically from smallest to largest and find the lower quartile, median and upper quartile. The median is 2, the lower quartile (the median of the values less than the median) is 1 and the upper quartile is 3. Thus the box extends from 1 to 3 are there are no whiskers.

What percent of the sophomores spend more than 60 minutes on homework per night?

25%
7. 25% of the sophomores spend between 48 & 60 minutes per night on homework.

How do you find Q1 and Q3?

Q1 is the median (the middle) of the lower half of the data, and Q3 is the median (the middle) of the upper half of the data. (3, 5, 7, 8, 9), | (11, 15, 16, 20, 21). Q1 = 7 and Q3 = 16.

How do you read a boxplot?

Definitions

1. Median. The median (middle quartile) marks the mid-point of the data and is shown by the line that divides the box into two parts.
2. Inter-quartile range. The middle “box” represents the middle 50% of scores for the group.
3. Upper quartile.
4. Lower quartile.
5. Whiskers.

What does an outlier on a graph mean?

An outlier is a value in a data set that is very different from the other values. That is, outliers are values unusually far from the middle. Also plotting the data on a number line as a dot plot will help in identifying the outliers.

How do you compare two box plots?

Guidelines for comparing boxplots

1. Compare the respective medians, to compare location.
2. Compare the interquartile ranges (that is, the box lengths), to compare dispersion.
3. Look at the overall spread as shown by the adjacent values.
4. Look for signs of skewness.
5. Look for potential outliers.

What does it mean if a boxplot is negatively skewed?

Negatively Skewed : For a distribution that is negatively skewed, the box plot will show the median closer to the upper or top quartile. A distribution is considered “Negatively Skewed” when mean < median. It means the data constitute higher frequency of low valued scores.

What a box plot tells you?

A boxplot is a standardized way of displaying the distribution of data based on a five number summary (“minimum”, first quartile (Q1), median, third quartile (Q3), and “maximum”). It can also tell you if your data is symmetrical, how tightly your data is grouped, and if and how your data is skewed.

What is the 5 number summary for a box and whisker plot?

A box and whisker plot-also called a box plot-displays the five-number summary of a set of data. The five-number summary is the minimum, first quartile, median, third quartile, and maximum . In a box plot, we draw a box from the first quartile to the third quartile. A vertical line goes through the box at the median.

What is the purpose in a box and whisker plot?

A Box and Whisker Plot is a graphical method for creating and displaying a specific data set . It is often referred to as a box plat or a box and whisker diagram. The diagram is most often used with historical data to provide an analysis of performance over time (for instance, with individual stocks).

What are the advantages of box and whisker plots?

Box and whisker plots offer the following advantages: They take up less space. Box and whisker plots use less space when compared to other types of data graphs and charts. They give you information as a whole. Whereas other graphs show you individual changes among data, you can use box and whisker plots to identify trends as a whole. They show outliers. You can compare data much quicker.

What is the lower quartile on a box and whisker plot?

The lower quartile (of a box-and-whisker plot) is the median of the lower half of the data.