READING A STEM AND LEAF PLOT MINITAB

In This Topic Step 1: Here’s what Minitab’s stem-and-leaf plot of the 64 IQs looks like:. It still accumulates the values from the top and the bottom, but it stops in each direction when it reaches the row containing the middle value median of the sample. Thus, the first row of the plot represents sample values of approximately 80, 82, and Outliers Outliers, which are data values that are far away from other data values, can strongly affect your results. The leaf unit is 0. If the sample is greater than 50, the data points on the plot may extend too far, and the distribution may be difficult to assess. The “leaf unit” at the top of the plot indicates which decimal place the leaf values represent.

Examine the center and spread of the distribution. The leaf unit is 1. Instead, you’d probably want to let some statistical software, such as Minitab or SAS, do the work for you. Then, ignoring the first column of numbers for now, the second column contains the stems from 6 to When you opt to use two rows for each stem, the first row is reserved for the leaves 0, 1, 2, 3, and 4, while the second row is reserved for the leaves 5, 6, 7, 8, and 9. Sometimes the one row per stem option produces the better plot, and sometimes the two rows per stem plot option produces the better plot.

For example, the first number in the depths column is a 1. A scientist for a company that manufactures processed food wants to assess the percentage of fat in the company’s bottled sauce.

Look for indicators of nonnormal or unusual data. Let’s take a look at another example. Thus, the first row of the plot represents sample values of approximately 80, 82, and Thus, the first row of the plot represents sample values of approximately 80, 82, and Try to identify the cause of any outliers. Our IQ data set produces stems 6, 7, 8, 9, 10, 11, 12, 13, and Stsm the key characteristics Examine the center and spread of the distribution.

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The second number in the depths column is also a 1. Now, back to that first column of numbers appearing in Minitab’s plot.

Stem and Leaf Plot

Create a stem-and-leaf plot of the data. When you opt to use two rows for each stem, the first row is reserved for the leaves 0, 1, 2, 3, and 4, while the second row teading reserved for the leaves 5, 6, 7, 8, and 9.

Sample size N The sample size can affect the appearance of the graph. For each row, the number in the “stem” the middle column represents the first digit or digits of the sample values. The decision to use one or two rows for the stems depends on the data.

In This Topic Step 1: The stem-and-leaf plot with right-skewed data shows wait times.

Stem-and-Leaf Plots | STAT /

Note, though, that Minitab uses two rows for each of the stems 7, 8, 9, 10, 11, 12, and Examine the center and spread of the distribution. Examine the center and spread of the distribution. Normal Distributions Section 4: Because a stem-and-leaf plot represents each data value, it is best when the sample size is less than approximately Assess how the sample size may affect the appearance of the stem-and-leaf plot.

The values range from 80 seconds to seconds. Outliers Outliers, which are data values that are far away from other data values, can strongly affect your results. Sample size n The sample size can affect the appearance of the graph. Minitab orders the data before producing the plot, and thereby creating what is called an ordered stem-and-leaf plot.

We could divide our first data point,for example, into a stem of 11 and a leaf of 1.

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Here’s what Minitab’s stem-and-leaf plot of the 64 IQs looks like:. One primary disadvantage of using a histogram to summarize data is that the original data aren’t preserved in the graph. A few items fail immediately and many more items fail later. When to use an alternate graph Because a stem-and-leaf plot represents each data value, it is best when the sample size is less than approximately The resulting 64 IQs are as follows:. The value for a row below the median represents the total count for that row and all the rows below it.

When data are skewed, the majority of the data are located on the high or low side of the graph. When data are skewed, the majority of the data are located on the high or low side of the graph. Outliers, which are data values that are far away from other data values, can strongly affect your results. If your data are skewed nonnormalread the data considerations topic for the analysis to make sure that you can use data that are not normal.

Center and spread Examine the following elements to learn more about your sample data. That column contains what are called depths. Bayesian Methods Section Skewed data When data are skewed, the majority of the data are located on the high or low side of the graph.

Stem-and-Leaf Plots

Multi-modal data Multi-modal data have more than one peak. Outliers, readiny are data values that are far away from other data values, can strongly affect your results.

The following stem-and-leaf plot shows customer wait times.