FREQUENTLY ASKED QUESTIONS
Q: How do I get the results from this program into court?
A: The methodology upon which this program is based is the only methods that have been empirically tested to be reasonably accurate. The method has been peer reviewed, the accuracy of the program can be stated and the research has even won awards!
The US Supreme Court has indicated that the evidence should meet the following guidelines.
* - Is it a testable theory or technique?
A. Yes, DRIVE3 has now been compared to 240 real life emergency responses and has predicted the actual response times within 39% nearly 75% of the time and the algorithms are based upon over 10,000 subject responses in research studies.
* - Is it peer reviewed?
A. This research has been peer reviewed by members of the engineering and psychology departments at the University of Hartford, it has been peer reviewed by awards committees (Jeff Muttart has received two awards for this research) and it has been peer reviewed by SAE, ITAI and ASPACI.
* - Is the error rate known?
A. Yes, all six current modules (path intrusions, vehicle following, vehicle approaching and traffic signals) report "Standard precision range". The standard precision range offers the user both the standard deviation of responses and the precision of the program itself for that type response.
* - Generally accepted within the field?
A. Yes, the program is now used in most states and Canadian provinces and is also used in Poland, New Zealand, Australia, England (and several other countries),
Q: Does DRIVE3 meet the Frye Standard (Generally accepted within the field & not based upon novel or new methods) -
A: DRIVE3 simply reports how drivers have responded in in research and real life from 1938 to 2004. It specifically culls out the data so as to report the average and range of response times for fairly specific situations. This is not new, there have been response time studies that have shown that response time varies in response to different situations since the 1860's. So reporting response times and measuring driver response times for different situations has been generally accepted for over 140 years. This means that this is not a new or novel approach. The only new aspect of DRIVE3 is that no one has ever compiled this extensive a list of studies before and no one has ever devoted as much time to the research of estimating driver response time before.
Q: I really do not understand where the equations came from, will I have a difficult time explaining this program in court?
A: You shouldn't unless you profess to knowing more than you do. It would be impossible to recreate the over 1 billion calculations that went into the derivation of the equations. What you do know is that the methodology was reasonably sound, it is based upon how drivers have performed in research and real traffic (over 20,000 responses), it has been proven to be relatively accurate (within 1/2 second 74% of the time) and there is no better tool available. The program is being used by over 300 reconstructionists, engineers and police officers in 9 different countries. Also you should make sure that you understand how to use the program.
Q: Can you explain the science behind the equations?
A: The equations are developed using Multiple Linear Stepwise Regression. You already use linear regression equations in your reconstruction, when you use stiffness coefficients in speed from collision damage calculations (A and B stiffness). The only difference is that instead of comparing crush depth to speed, we are comparing several variables to driver response time in a "stepwise" manner. To explain the "Stepwise" process, I will use an analogy of a professional association, the stepwise method checks credentials before membership rather than letting everyone be a member, and then checks with previously admitted members to make sure they still qualify for membership every time a new member is added. This is why Stepwise regression has been referred to as the "Surest path to an accurate predictor".
Q: I have heard that social sciences are "soft sciences" and therefore are not regarded as scientific, is that true of DRIVE3?
A: If a Judge or Lawyer suggests that DRIVE3 is soft science, then they are just ignorant of the relative law. Soft science involves issues where precision and accuracy of a method cannot be stated. DRIVE3 offers both. Soft science may not be empirically based, DRIVE3 is. The research cited regarding driver response may have roots in psychology (a social science), but it is based upon a validated mathematical analysis that has been shown to be able to estimate driver response within a stated accuracy and precision, which is the definition of a “hard” science. DRIVE3 reports the anthropometric distribution of response times by reporting response times very much like an anthropometric chart estimates the distribution of heights and weights of the population.
Q: How do I know which response type to select?
A: By the direction of the hazard relative to the responder. If in-line with the responder it would be vehicle following. If moving somewhat across the road, then it is a path intrusion. If one driver is cutting off another and both were traveling in the same direction it would be addressed by the vehicle changing lanes module.
Q: Is this the program that we should be using for estimating the response time in all our cases for now on?
A: It depends upon your case. Like any other tool it has limitations. There will be some crash situations that will simply not be able to be estimated by this program. As with any building, this program is only as good as its foundation and we clearly need more research into driver response times. You should always consider the acronym IN CAR CREED before applying any "perception"-response time to a situation. If applied correctly, DRIVE3 has been shown to be an effective tool for estimating driver response times.
Q: I noticed that the program does not ask for the driver's eyesight, age, gender or athleticism, don't these factors make a big difference?
A: Not based upon all the research when put together. In general no study has ever shown that static eye acuity alone is related to slower responses or greater accident rates. Older drivers have been shown to be over represented in intersection collisions and have reduced contrast sensitivity, but based upon the available information that difference is not consistent, predictable or statistically significant (every so often you get a really slow older responder). This program was designed to estimate the response times of drivers based upon the scenario they face regardless of individual characteristics and it has been proven to be relatively accurate. Also recall that DRIVE3 offers "Perception"-Response times, older drivers may likely respond differently than a younger driver during detection and before "perception" is attained. However, based upon the available research, older drivers' PRT have not been statistically dissimilar after perception is attained.
Q: Would an individual's personal information assist us in making a better estimate?
A: Perhaps if we had a great deal more research available for every possible difference under every possible scenario, but at the present time there is no individual characteristic that can be relied upon to be associated with a difference in driver response time in a predictable way. This is why the program centers upon methodology & environmental factors, which have resulted in reasonable accurate estimations.
Q: How much longer does it take a drunk or fatigued driver to respond?
A: There is simply not enough information available to give an assessment such as this. Further general rules-of-thumb have been proven to be wrong more than they are right. A better approach is to reconstruct the collision and the response time of an average driver under the circumstances and if the driver performed poorly, then you can state that the reason for the poor performance may have been due to the fatigue or alcohol consumption. However, if there is evidence that the driver responded in a timely manner, then you have no evidence that fatigue or alcohol influenced his or her response. Regarding the use of alcohol consider DATT. Dosage, Absorption, Tolerance & Task.
Q: I would like to load the program onto my laptop and desktop, does that cost more?
A: No, you can load it as many times as you wish. However, your name will appear on all work. If you should produce work with the name of another registered person, it would be a copyright violation.
Q: What if I only want to load it onto one computer, do I get a discount?
A: No, the program is licensed to a person or agency, not to a machine
Q: Will this program become outdated?
A: Let's hope so. There is still so much more to be learned about driver response. This program allows the user to make a reasonable estimate of how drivers have responded to various scenarios most of the time, but much more can be done. Therefore, if the program becomes outdated, it is because more information becomes available. We will attempt to keep the program current as new information becomes available. Most updates will be free, however, if there is a major update necessary, there may be a nominal change.
Q: Will using this program make me healthy, wealthy, & wise?
A: If you are not healthy, wealthy & wise already and if you are unaware of the limitations of this program or do not know how to use it properly, then it will not be long before all three characteristics deteriorate. Remember that we are attempting to estimate the response of humans with all their differences (We are fishing with a net, not a spear). Also recall that you cannot predict the response time of a drunk man who is reading the paper, talking on his cell phone, blind in one eye and can't see out of the other. This program offers a mathematical estimate of response times based upon how drivers have performed and may not estimate the response time of the next driver, but the results do offer us a yard stick from which to compare.
Q: Isn't it true that a person's level of attention (vision, or some other variable) may influence a drivers response time?
A: Yes, anything could have a minor influence upon a drivers response but based upon research, DRIVE3 accounts for all the variables that were significantly associated with driver response times for the types of situations analyzed.
Q: Has this research been peer reviewed?
A: Yes, it was part of a master's thesis where is was reviewed by the psychology and engineering departments at the University of Hartford. It was also reviewed by the committees for the Wallace Research Award and the Graduate Research Awards. Subsequently, the research has been used by several members of the accident reconstruction community and analysts from 6 countries and over twenty states are registered users of the DRIVE3 computer program. This research has also been peer reviewed by the Society of Automotive Engineers before publication of SAE paper 2003-01-0885. Rarely has there been research that has had more peer review.
Q: Are you (the user of DRIVE3) a human factors expert?
A: Yes to the extent that I am an [accident reconstructionist/engineer] and this research has been part of the training in my field.
Q: Should this driver have been more attentive?
A: Attentive to what? Attention is a narrowing of focus. Drivers are always attentive, but not always to the appropriate thing. If a driver is too attentive then he becomes impulsive and starts to brake and/ or swerve when it is inappropriate. If you are being more attentive to the children at the roadside then you are being less attentive to the vehicle stopped in front of you.
Q: How do I know if the driver's response was negligent?
A: The purpose of this program is to report the average response time and the range associated with that response. This program offers a yard stick from which to compare. It is then up to a judge or jury to determine if the response was negligent.
Q: If the driver was not wearing his or her glasses at the time, how would that change your opinion?
A: Unless the driver was legally blind or worse, there is no reason to believe that it would. He did not have to read the pedestrian or car, he just had to see it was there.
Q: What is the process of human sight?
A: My research deals with observations of driver response, not eyesight. I have no opinions regarding eyesight. This program has reasonably estimated the response times of real drivers in traffic situations regardless of their individual characteristics.
Q: Isn't it true that some driver may respond faster or slower than others?
A: Yes, within a range if both drivers are engaged in similar tasks.
Q: What does DRIVE3 stand for?
A: Driver Response in Various Environments Estimated Empirically.
Q: Does Drive3 factor in available lighting – either/or vehicle head lighting and/or street lighting? If so, can the parameters specific to each case be entered?
A:
DRIVE3 is based upon what was reported in research (over 10,000
responses) and based upon how 147 drivers have responded in real life situations.
In all the real traffic incidents to date, the scene had been lighted.
No driver response time study has ever measured driver response time
relative to street lighting or headlights.
Most nighttime response research measured Time or "Distance to
impact", not "perception-response".
DRIVE3 reports driver response time and is only as good as the research it is based
upon. Therefore, it is probably
only applicable to lighted roads and daylight when dealing with diffuse
reflectors (pedestrians, animals, etc…). DRIVE3
does not eliminate the need for user expertise when dealing with illuminated areas,
and when dealing with poor
contrast and/or low light areas and diffuse reflectors.
Research has shown that the DRIVE3
program has estimated the response
time of drivers at day and night within reason on lighted roads.
If there is a lighting issue that is much different than the manner in which the available research has been gathered, then DRIVE3 is probably not the tool to be used if the user does not have expertise in nighttime response issues.
Q: Does DRIVE3 account for driver vision
A: No, DRIVE3 has been specifically designed to attempt to estimate response times for all drivers regardless of individual differences.
Q: Is the "Absolute threshold" reported in the vehicle following section the point that the driver should be able to first see the vehicle ahead? If so, it does not seem correct, because I could see the lead vehicle from over 1/2 mile away.
A: The absolute threshold is not the "seeing" distance, it is the threshold at which 50% of drivers will be able to detect the relative velocity between their vehicle and the lead vehicle. Up until that point, they may "see" the lead vehicle, and they may be able to detect that they are "closing upon" the lead vehicle, but they will not likely be able to understand that they are closing upon the lead vehicle at a dangerous rate until they reach that threshold. Also, the absolute threshold is WHERE DRIVERS "MAY" DETECT, NOT NECESSARILY WHERE THEY "DO" DETECT. This of course assumes that there is enough information to allow the following driver to see the full size of the lead vehicle. However, with adequate context (typically topographical cues, the typical response time is relatively fast).
Q: I have a case involving a person laying in the road and the driver never responded, can I use DRIVE3 to estimate the average response for that situation?
A: NO! DRIVE3 is designed to estimate the average response time for several situations, but there must be a clearly defined stimulus. Consider the acronym IN CAR CREED and understand that a driver will not likely perceive a problem until it is EASILY identified as and IMMEDIATE hazard. DRIVE3 will usually underestimate response times when there is a longer than normal time for the driver to reach a detection threshold such as darkly clad pedestrians on unlighted roads, objects in areas of uneven lighting, poor pattern recognition situations and when "perception as a hazard" does not occur immediately (A vehicle or pedestrian is seen for several seconds but the driver does not recognize the vehicle or pedestrian as a hazard until much later).
Q: You report MEAN or AVERAGE response time. Isn't it true that because response times have a skew distribution that the number DRIVE3 reports will be higher than the median response?
A:
Based upon the current research, no there is not a significant
overestimation and to imply one would lead to being incorrect nearly 47% of the
time. The only authors who have implied that response times are skewed are
those who measured the response times of subjects while not engaged in the
driving task, or while responding to a known light stimulus or who lumped less
complex response results with more complex response results. Based upon
the research from 145 studies (involving over 10,000 responses) and 247 real life responders, all data lumped
together offers a multi-modal distribution, not a skew and if looking at like
events that involve the driving task, the data is uniformly distributed when
enough data is collected. Regardless, the comparison of the equations to
the real life data used the Wilcoxon Signed Rank Test which assumes a
non-parametric (not bell shaped) distribution to account for the possibility that due to lack of
data the responses have not yet reached a uniform distribution. That
being said, the MEAN reported by DRIVE3 is typically equal to the
52nd percentile response, but the difference is not statistically significant
and is not consistent enough in individual cases to rely upon (DRIVE3 has
overestimated and underestimated the actual response time nearly equally).
Q. I have been told that DRIVE3 needs to be tested further before I can use it in court, is that true?
A. Right now, DRIVE3 is directly based upon how over 10,000 drivers have responded in research and how 247 drivers have responded in real life. Basically, DRIVE3 has proven that the real life drivers respond similarly to the subjects in research if the different methodologies are accounted for. DRIVE3 is based upon ten times the responses of the next most study and right now is based upon the responses of 247 more real life responses than the next closest study.
Q. I was always told that 1.6 seconds was a reasonable response that would account for most drivers and most situations, are you telling me that is wrong?
A. A driver's response changes. If the stimulus (hazard) changes, then so will the response in most cases. There are a few instances where 1.6 seconds may be a reasonable estimate. However, based upon the 247 real life responders, 1.6 seconds was not within 1/2 second of the actual response time 47% of the time. Therefore, if using that figure for all cases, you would be wrong as much as you would be right.
Q. What if I use the range of 0.75 to 1.5 seconds?
A.
Again, rule-of-thumbs simply do not work. This range does not estimate the
real life responders more than 60% of the time and this range will be wrong 99%
of the time for most complex situations such as closing on the rear of a vehicle
that is stopped on a highway, a dark pedestrian at night or a multiple stimulus
event.