----------------------------Original message---------------------------- When I wrote that I was offended by the statement of the NPR radio interviewer that the hiker had an inaccurate map, I was not bothered by the fact that a USGS quad might contain an error. If the lost hiker had said his map was inaccurate, that would have been fine. But he did not make that claim. He said he misread his map. It was the interviewer who seemed to associate that with an inaccurate map. This discussion has been interesting. Somewhere the discussion turned to USGS quads. Those were never mentioned in the radio interview. We have no evidence the hiker had a quad map. How would the discussion have changed if we assumed he was using a 1:250,000 topo sheet, or a highway map? With my interest in map use, I would like to know if the hiker had a map that was usable for his tasks. It is likely that there is no map available for that area that would give the hiker all he would like to know. Even if he used a 1:24,000 quad it is probably dated in terms of trails and shelters, if any. And, those quads are quite generalized. Quad maps were not designed for hikers. I too have used these in mountains and know there are significant features on the ground that do not show up on the maps. In the mountains, it is hard to determine which of the significant features are on the maps. When I worked for USGS many years ago, I remember a colleague telling me about his experience as a stereophoto plotter. He said he labored one day to shape the contours defining some hogbacks in the Colorado Rockies. Then at the end of the day his supervisor came by and told him he was too detailed. The supervisor took an eraser and smoothed our the contours to make them more generalized. This story tells me why those small but significant features in reality do not appear 1:24,000 quads. And, we should acknowledge that 1 inch to 2,000 feet is not very large scale. There is much generalization in that scale. This discussion has also made me reflect on what makes a map inaccurate. To determine accuracy, you have to have a standard to judge against. We do not have very good accuracy standards to judge our maps. If a topo sheet has two geographic names misspelled, one name misplaced, two contours mislabeled and a perennial stream misidentified as a permanent stream, should we say this is an inaccurate map? Or, do we say we have identified some errors on the map? In football, when the ball is kicked between the uprights we say the kicker was accurate. If it does not pass between the uprights then no points are given. WE will never be able to have such accuracy standards in cartography and therefore I think we should be very careful about calling maps accurate or inaccurate. I would rather look at the usability of a map for given tasks. This is implicit in our efforts to develop metadata standards for datasets. We also should look at the user to see if he or she has the ability to use the map for a given task. Do map librarians have insight on this subject? --------------------------------------------------------------------- Dr. James R. Carter, Professor, Geography/Geology Department Illinois State University, Normal, IL 61790-4400 USA Director, Laboratory for Integrated Learning and Technology at Illinois State University, and Chair, Map Use Commission of the International Cartographic Assocation tel: (309) 438-2833 fax: (309) 438-5310 [log in to unmask] ----------------------------------------------------------------------