1. Timothy Ludwig & David Goomas ABA 2006
Voice Picking vs. Bar Code Scanner: Providing Immediate Feedback to increase Productivity and Reduce Errors
Timothy Ludwig & David Goomas
ABA 2006

2. Take these warehouse workers doing their job
Errors:
Shorts
Mispicks
Overs
Damages
Productivity:
The amount of time it took to complete the order
# cases per labor hour

3. A - Antecedent B - Behavior C - Consequence The Three-Term Contingency
The closer in time these contingencies occur
the greater the behavior change

4. The Problem
Managing performance in the real world has been hampered by:
• Antecedents (e.g., response information) that are not proximal to the behavior they prompt or easily accessible in the work process.
• Behaviors that cannot always be reliably measured.
• Consequences that are delayed from the occurrence of the behavior.

5. Paper-Based Selection
Order information and location provided on paper list
Given Feedback on productivity at end of cycle/day/paycheck
Given Feedback on errors at paycheck SD
SRdistal
SRdistal

6. Bar Code Scanners
Visual Order information and location provided on-screen
Given Immediate Visual Feedback on productivity
Given Immediate Visual and Auditory Feedback on errors SD
SRproximate
SRproximate

7. Voice Picking
“Hands free - Eyes free”
auditory Order information and location provided in headphones
Given Immediate auditory Feedback on errors
Given auditory Feedback on productivity on request SD
SRproximate
SRproximate

8. Both Scanning and Voice make contingencies proximal to behavior

9. Reports from vendors, trade journals, and logistics consultants
Miller (2004) reported productivity gains of 8% to 15% when comparing hand-held scan selection to voice selection.
These results would seem to justify the extra cost of implementing voice technology (vs. hand-held technology) within the distribution warehouse.
(cf. Lacewell, 2004; Miller, 2004; Wulfraat, 2002)

10. The purpose of this field report was to investigate the migration from hand-held scanners to voice-directed wireless computers on work-force productivity and accuracy.

11. As opposed to Paper-based selection,
both Scanning and Voice offer real-time productivity goals.
Scanning and Voice also provide immediate auditory feedback and work flow consequence if an accuracy error occurs.

12. There is an ergonomic difference
Over the course of an 8-hr shift, the order selector may handle the handheld scanning unit 800 to 1400 times, much of it including placement in and out of the holster.
The Voice headset unit does not require handling thereby reducing the need for extra physical steps during the selection process.

13. This may lead to productivity gains
It was expected that productivity and accuracy would improve for voice compared to scanning since voice has fewer interrupt points leaving both hands and eyes available for warehouse operators to perform their task.

14. The study was conducted at two auto-parts distribution centers operating 3 shifts, 5 ½ days a week.
An experimental group and three comparison groups were used

15. multiple baseline design across departments
Baseline collected for two weeks at both distribution centers (experimental and comparison).
Voice technology was implemented at the experimental distribution center in the Battery and Tire departments first followed by the Accessories department three weeks later.

16. paper and handheld comparisons
Similar departments at the comparison distribution center continued using handheld computers in tires, batteries, and accessories throughout the study.
Comparison departments within the experimental DC continued using paper or handheld methods.

17. Department Baseline Intervention Participant # Experimental Handheld
Voice
4 - batteries
4 - tires
6 - Accessories
Comparison
Same job- different DC
3 - batteries
4 - Accessories
Same DC - diff job
Paper 7 15

18. productivity
The dependent variable for selection productivity was the departmental average units (DAU). A unit could be a single battery, a single tire, a single mirror, or a single case. The formula was:
Departmental Average Units (DAU) =
total units / selection hours of department

19. accuracy
Mispicks. A mispick occurred if the selector picked a wrong case.
o Mispicks = total line errors / total lines picked.
Over/Shorts. If the selector picked too many or too few cases of the correct item, the error showed up as an over/short error.
o Over/shorts = absolute value of unit errors / total units picked.

20. Baseline DAU = 137.4 Intervention DAU = 156.3 13.7% increase

21. Baseline DAU = 133 Intervention DAU = 161 21% increase

22. Baseline DAU = 169 Intervention DAU = 200.8 18% increase

23. Paper = 3.5% Handheld = .2% Voice = 1.06%

24. Paper = 2.5% Handheld = .04% Voice = .02%

25. Productivity gains in Voice
Voice technology results were immediate and sustainable in three key sections of the warehouse
showing productivity increases of 13%, 21%, and 18% respectively, or an average of 17%.
This is consistent with Miller’s (2004) report on grocery chains.

26. Productivity gains in Voice
selectors using handheld scanners had to use an estimated time of 8-10 seconds to handle the scanner during each pick.
selectors using the voice system could maintain eye contact with the product as they listened for information. The only product verification was oral which reduced the need for body movement
Voice selectors were also less likely to stop their order runs to socialize with other workers.

27. Accuracy comparison
Handheld and voice selection had significantly fewer errors than paper

28. Accuracy comparison
Mispicks were higher for voice selection than handheld scanning
This may be due to scanning’s ability to catch upstream errors.
The selector may pick from a location where the wrong product placed by replenishers.
Upstream errors can be detected since the order selector is scanning the UPC on the actual item.

29. Accuracy comparison And Voice’s inability to catch upstream errors.
Selectors using Voice are reading the check string on the slot to verify location instead of verifying the actual item.
Therefore, we saw spikes in mispick errors on certain days when replenishment errors occurred.
With voice, some selectors asked for additional information, such as item description, to compare with the product’s markings.

30. Questions?