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#31
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
In article , just me wrote:
"David desJardins" wrote in message ... Aula writes: So what are the usual applications in real life? Kevin posted a good example: giving the distribution of test scores to the students in his class. It's a graphical representation of the data, which also gives all of the raw data to the students, so if they want to know (for example) how many students scored above them, the data is right there. Are there any other applications that are used at least in research or something? While students may like to know grade distributions, that isn't quite what I was thinking of as "real life"..... What is the real value of knowing this type of representation of data? Well, for some of us, preparing grade distributions IS real life. According to Tufte, in "The Visual Display of Quantitative Information", stem-and-leaf plots were invented by John Tukey (a famous statistician---see http://www-gap.dcs.st-and.ac.uk/~his...ans/Tukey.html). This book is probably the first exposure many people (including me) had to stem-and-leaf plots. I think that Tufte's book would be an excellent text for middle-school or high-school students, as it describes quite clearly how to present data well. Tufte quotes Tukey as saying "If we are going to make a mark, it may as well be a meaningful one. The simplest---and most useful--meaningful mark is a digit." Tufte gives one example of stem-and-leaf plots for the heights of 218 volcanoes. Note: Tufte dedicates one page of his 190-page book to stem-and-leaf plots, so clearly he does not regard them as a major topic. They are in the chapter on "multifunctioning graphical elements," which includes a number of weird and wonderful ways of displaying data. My personal belief is that stem-and-leaf plots are a very minor data presentation trick that is handy to know but not worth putting into curricular standards. Scatter diagrams, contour diagrams, and false-color presentation are all much more important. -- Kevin Karplus http://www.soe.ucsc.edu/~karplus life member (LAB, Adventure Cycling, American Youth Hostels) Effective Cycling Instructor #218-ck (lapsed) Professor of Computer Engineering, University of California, Santa Cruz Undergraduate and Graduate Director, Bioinformatics Affiliations for identification only. |
#32
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
In article ,
"just me" wrote: "David desJardins" wrote in message ... Aula writes: So what are the usual applications in real life? Kevin posted a good example: giving the distribution of test scores to the students in his class. It's a graphical representation of the data, which also gives all of the raw data to the students, so if they want to know (for example) how many students scored above them, the data is right there. Are there any other applications that are used at least in research or something? While students may like to know grade distributions, that isn't quite what I was thinking of as "real life"..... What is the real value of knowing this type of representation of data? -Aula Personally, I think it is valuable to have a lot of different tools at your disposal to graphically represent data. You never know which ones will make some piece of information or some connection suddenly leap out or make more sense. You can also use it to compare two different sets of data: say, scores from two different classes, by putting the "stem" in the middle of 3 columns, and the "leaves" (the details from each class) in the two side columns. I'd never heard of leaf-and-stem (or at least didn't remember hearing about it) until I read this thread, but it took me about 10 minutes to find a decent explanation on a web page, and another 2 minutes to understand it. I think it may come in handy when I'm looking at some sorts of statistical data -- attendance figures, maybe -- but I'm not sure yet. I also showed it to a friend who is a technical writer, and she said she thought she could see applications for it, and was pretty interested. I asked both of my 17 yo's if they knew about it; one said yes and he could explain it (he's a math sponge) and the other remembered the words but couldn't remember what it was (she does her best to pretend school doesn't exist at all), so obviously they ARE teaching it around here. meh -- Children won't care how much you know until they know how much you care |
#33
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
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#34
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
just me wrote:
"David desJardins" wrote in message ... Aula writes: So what are the usual applications in real life? Kevin posted a good example: giving the distribution of test scores to the students in his class. It's a graphical representation of the data, which also gives all of the raw data to the students, so if they want to know (for example) how many students scored above them, the data is right there. Are there any other applications that are used at least in research or something? While students may like to know grade distributions, that isn't quite what I was thinking of as "real life"..... What is the real value of knowing this type of representation of data? -Aula There are tons of applications. This type of analysis is probably descriptive that you use to look at the (usually categorical) data to check for its validity. For example, in some sort of medical research, patients may have their age, weight, temperatures recorded. Although you can present summary stats (e.g., average, median, mode, etc.) of each variable, the stem and leaf plot can show you a rough distribution and from there you (the researcher) can figure out the average, median, mode. That said, the stem-and-leaf plot isn't used a lot in social science research when descriptive statistics is requested. Jeanne |
#35
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
"Bruce and Jeanne" wrote in message
... There are tons of applications. This type of analysis is probably descriptive that you use to look at the (usually categorical) data to check for its validity. For example, in some sort of medical research, patients may have their age, weight, temperatures recorded. Although you can present summary stats (e.g., average, median, mode, etc.) of each variable, the stem and leaf plot can show you a rough distribution and from there you (the researcher) can figure out the average, median, mode. That said, the stem-and-leaf plot isn't used a lot in social science research when descriptive statistics is requested. Now that makes sense to me. I appreciate your explanation as I was having a hard time figuring out uses. Since I work in the social sciences I might not think as quickly of hard science applications ;-) -Aula -- see my creative works on ebay under aulame 123 |
#36
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
just me wrote:
"Bruce and Jeanne" wrote in message ... There are tons of applications. This type of analysis is probably descriptive that you use to look at the (usually categorical) data to check for its validity. For example, in some sort of medical research, patients may have their age, weight, temperatures recorded. Although you can present summary stats (e.g., average, median, mode, etc.) of each variable, the stem and leaf plot can show you a rough distribution and from there you (the researcher) can figure out the average, median, mode. That said, the stem-and-leaf plot isn't used a lot in social science research when descriptive statistics is requested. Now that makes sense to me. I appreciate your explanation as I was having a hard time figuring out uses. Since I work in the social sciences I might not think as quickly of hard science applications ;-) -Aula I can also see social science applications. For instance, in transportation planning one might send out a survey asking people about the number of cars in their household, the number of drivers, the number of bicycles, and the primary mode of transportation. Stem-and-leaf plots can quickly point out outliers (e.g., a household with 10 cars). In another application (stop me, please!) can be in education policy looking at use of PSATs: grade of student when PSAT taken, PSAT score. Again stem-and-leaf plots would show outliers (e.g., the 5th or 6th grader who took it). But as a SAS programmer, I've never had a researcher ask for a stem-and-leaf plot. They want the summary statistics. Jeanne |
#37
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
On Fri, 17 Oct 2003 19:31:31 EDT, H Schinske wrote:
wrote: It's a graphical representation of the data, which also gives all of the raw data to the students, so if they want to know (for example) how many students scored above them, the data is right there. So basically it's the same thing as a bar graph with raw data scrawled on it? ;-) Well, as someone who works in the publishing/printing industry, my first thought was, "Interesting... but with the right data set and a proportional font, the plot comes out totally misleading." I.E, if a leaf has several digits that are narrower than the average; for example, there are lots of '1's, and other leaves have lots of '5's, which are wider, then even if there are *more* data points in the first leaf than the second, it will physically take up less space on the page, and mislead the reader. So, unless the person presenting the data is very careful about typographic conventions, the end result would present an inaccurate view of the data. Personally, I would just prefer a bar chart, and have the raw data presented elsewhere. ;-) - Rich |
#38
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
In article , user wrote:
Well, as someone who works in the publishing/printing industry, my first thought was, "Interesting... but with the right data set and a proportional font, the plot comes out totally misleading." BEEP! You can't use stem-and-leaf plots with proportional fonts! Mono-space fonts only!!! (Or very difficult tabular typsetting to force each digit to have the same width.) -- Kevin Karplus http://www.soe.ucsc.edu/~karplus life member (LAB, Adventure Cycling, American Youth Hostels) Effective Cycling Instructor #218-ck (lapsed) Professor of Computer Engineering, University of California, Santa Cruz Undergraduate and Graduate Director, Bioinformatics Affiliations for identification only. |
#39
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
On Sun, 19 Oct 2003 18:51:57 EDT, Kevin Karplus wrote:
In article , user wrote: Well, as someone who works in the publishing/printing industry, my first thought was, "Interesting... but with the right data set and a proportional font, the plot comes out totally misleading." BEEP! You can't use stem-and-leaf plots with proportional fonts! Mono-space fonts only!!! (Or very difficult tabular typsetting to force each digit to have the same width.) And even worse, in the context of this thread, most people write in a more-or-less proportional fashion, so the kids could easily end up misleading themselves with their own hand-drawn plots, unless they are done in graph paper, to ensure that each digit takes up the same amount of space. |
#40
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POLL: Math questions regarding upper elementary school (xpost to m.k.)
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