For the second question, Young and Veldman give the reason as one of communication. We (usually) read from left to right, so the first column of numbers makes obvious the interval size being used. For my class I use an example such as, try counting to 100 by 5's starting with 15 then try it starting at 17. -- Doug Wallen, Psychology Dept. (507) 389-5818 Minnesota State University, Mankato [EMAIL PROTECTED] 23 Armstrong Hall Mankato, MN 56001
> From: "John W. Kulig" <[EMAIL PROTECTED]> > Reply-To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > Date: Fri, 15 Feb 2002 15:45:05 -0500 > To: "Teaching in the Psychological Sciences" <[EMAIL PROTECTED]> > Subject: Two boring stat questions > > Tipsters: > Question 1. Most texts do frequency distributions from highest to lowest > score, as in: > > X tally > 34 xx > 33 xxxxx > 32 xxxxxxx > . > Has there ever been any reason to list from high to low?? It seems > to me that you'd want to list from low to high, this is the custom for > other techniques such as stem-n-leafs and histograms. Indeed, if you are > going a tally, you can simply rotate the frequency histogram 90 deg > counterclockwise and get a histogram for no extra cost. A few books > listed from low to high (my preference) en route to a histogram - but > didn't call it a "frequency distribution." > Question 2. Some texts claim that when constructing grouped > frequency distributions, to make the stated lower limit of the first > interval evenly divisible by the interval width. So, if we had the > numbers 10,11, 12, 13, 14,14,14,15,16,16, and so forth, and chose an > interval width of 3, the intervals would be: > > 9-11 > 12-14 > 15-17 etcetera. > > What is the reason for the rule? I can only come up with one. If your > numbers get doen to zero or less than zero, you will have an interval > that starts with zero. In the above example, if you continued downward > you'd get to 0 - 2 (However, if plotted the data you'd use midpoints, > you generally label the interval by its midpoints). I played with > Minitab a little I generated a few histograms that, by default, violated > the rule. One would think grouped histrograms would obey the same rule. > Is this simply an relic from the past - that when people did these by > hand they wanted a standard rule to guarantee some uniformity?? > > -- > ------------------------------------------------------------------ > John W. Kulig [EMAIL PROTECTED] > Department of Psychology http://oz.plymouth.edu/~kulig > Plymouth State College tel: (603) 535-2468 > Plymouth NH USA 03264 fax: (603) 535-2412 > ------------------------------------------------------------------ > "One word of truth outweighs the whole world." > Russian proverb > ------------------------------------------------------------------ > > > > --- > You are currently subscribed to tips as: [EMAIL PROTECTED] > To unsubscribe send a blank email to [EMAIL PROTECTED] --- You are currently subscribed to tips as: [EMAIL PROTECTED] To unsubscribe send a blank email to [EMAIL PROTECTED]
