I think either is ok ..though my preference is histogram style. Even though (as Don says) the Likert scales are not necessarily "equal intervals" if we think about the relationship between our data and the true (unknowable) underlying function, I would consider the scales continuous as opposed to discrete (besides, can't a scale be continuous and _not_ equal interval?) . When we analyze the data we convert them to numbers and interpret the points _between_ two values ... this can't be done with blatantly discrete values such as political affiliations. You cant be half way between Democrat and Socialist if collected categorical style, but you _can_ be half way between agree and strongly agree, both as an individual response and a group average. I suspect (no firm data though) that most people, on most scales, treat them as continuous scales. I have seen enough people put their check mark half way two anchors on the scale. Also, when we write the scales we prod participants into responding as if it continuous with our verbal anchors such as _degree_ of agreement. Many of these scales have numbers and a continuous line prodding the participants to respond continuously as best they can.
Finally, from the "two wrongs don't make a right" department, statistically we often treat the data as equal interval, not ordinal. And finally finally, if we don't want to worry about the relationship between our crude measurements and the "true" underlying variable (the "IQ is what IQ tests measure" attitude) much of the agonizing about this issue goes away .. I think (but its late, thinking is hazardous past 9 pm!). So there are lots of forces pushing those little numbers into the continuous category ... good question Nancy. ========================== John W. Kulig, Ph.D. Professor of Psychology Coordinator, University Honors Plymouth State University Plymouth NH 03264 ========================== ----- Original Message ----- From: "Christopher Green" <chri...@yorku.ca> To: "Teaching in the Psychological Sciences (TIPS)" <tips@fsulist.frostburg.edu> Sent: Thursday, April 12, 2012 5:23:02 PM Subject: Re: [tips] Likert scale graph/chart results presentation If you want to be scrupulous, the "convention" (such as it is) is to use bar graphs (with spaces between the bars) whenever the values use along the horizontal axis are discrete, and a histogram (with bars touching each other) when the values along the horizontal axis are continuous. But the convention is violated so regularly, that it is only a convention in the minds of scrupulous statisticians. Chris --- Christopher D. Green Department of Psychology York University Toronto, ON M3J 1P3 Canada chri...@yorku.ca http://www.yorku.ca/christo/ ========================== On 2012-04-12, at 2:46 PM, drnanjo wrote: Hey gang: I am teaching an upper division research methods class for the first time in my life. As such, I want to be scrupulous about the guidance I give If one wishes to present likert scale results in pictorial form, would one do a histogram (continuous, with bars touching) or a bar graph (each point on the Likert scale represented by a bar? I am asking because the rules seem to be lose sometimes - for example, income is technically quantitative and ratio type data but some researchers divide income into "classes" and make a bar graph instead of a histogram or line graph. Thanks in advance for sharing the collective wisdom. Nancy Melucci (in this case) California State University in the Hills of Dominguez. ----- --- You are currently subscribed to tips as: chri...@yorku.ca . To unsubscribe click here: http://fsulist.frostburg.edu/u?id=430248.781165b5ef80a3cd2b14721caf62bd92&n=T&l=tips&o=17270 (It may be necessary to cut and paste the above URL if the line is broken) or send a blank email to leave-17270-430248.781165b5ef80a3cd2b14721caf62b...@fsulist.frostburg.edu --- You are currently subscribed to tips as: ku...@mail.plymouth.edu . To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13338.f659d005276678c0696b7f6beda66454&n=T&l=tips&o=17275 (It may be necessary to cut and paste the above URL if the line is broken) or send a blank email to leave-17275-13338.f659d005276678c0696b7f6beda66...@fsulist.frostburg.edu --- You are currently subscribed to tips as: arch...@jab.org. To unsubscribe click here: http://fsulist.frostburg.edu/u?id=13090.68da6e6e5325aa33287ff385b70df5d5&n=T&l=tips&o=17282 or send a blank email to leave-17282-13090.68da6e6e5325aa33287ff385b70df...@fsulist.frostburg.edu
