Type in every single observed leaf value for that stem, starting with the lowest one. Then look at all the observations you have for that stem value. Then type a bar or some other vertical device to separate your stem from your leaves. Once you have identified your stems and leaves, type the lowest stem value. It would be possible to use measurements in the hundreds or even thousands.ģ. Thus, the tens spot is the stem and the singles spot is the leaf in this case. If we were measuring temperature, for instance, it would be a lot more likely that the day would have temperatures like 56 and 58 than 60-something and 40-something. For a number like 57, the more durable part of the number is the ‘5’ because even if there was some variation in the measure, the number in the 10’s spot might not change but the ‘7’ in the singles spot is more sensitive and thus more likely to flutter like a leaf. The stem is the more durable part of the number and the leaf is the more sensitive part of the number. Think of each number as having a stem and a leaf.

And when I say ‘people’ used to prepare documents, I am actually imagining wives and girlfriends of the husbands and boyfriends who were preparing final drafts of their dissertations and later the (mostly female) secretaries, administrators, and lab assistants typing up articles and figures for (mostly male) professors.

It is a rather ingenious graphical device that could be created even with a typewriter, which is how people used to prepare documents not that long ago. Table 3.3.The stem and leaf diagram is an old stand-by that has largely been abandoned in social science as it morphed into the histogram. Stem-and-leaf plotĪ stem-and-leaf display or stem-and-leaf plot is just another way to present quantitative data in a graphical format, similar to a histogram because both types of charts group together data points, to assist in visualizing the shape of a distribution, they are very helpful ways in exploratory data analysis to visualize how many data points fall into a certain category or range.Įxample: let’s say we have the finishing scores of golfers in a round of tournament golf: 66, 67, 67, 68, 68, 68, 68, 69, 69, 69, 69, 70, 70, 71, 71, 72, 73, 75, 101, 102, 111 Stem

The frequency distribution of people ages at a home party. Frequency histogram is the same as a regular histogram, except values are displayed as percentage of the total of the data. We can transform the data table 3.1 into a relative frequency histogram by converting the numbers into frequencies. The way the data (people ages) is spread out in the histogram is called the distribution. The distribution of people ages at a home party. Each of these ages intervals should have the same size or length. Before creating the histogram, you might first group together 0 − 14 year-olds, 15 − 29 year-olds, 30 − 49 year-olds, etc. It is preferable to use a histogram instead of a bar graph when you have too many data points to plot individually.Įxample: you want to use census data to make a graph of the number of people of each age at a home party. Histogram differs from a bar graph in the sense that a bar graph relates two variables, but a histogram relates only one. It is an estimate of the probability distribution of a continuous variable which is why there are no gaps. A histogram also called a frequency histogram could be defined as an accurate graphical representation of the distribution of numerical data set.

Stem plot vs histogram