True OMR True OMR Second Darkest Mark DetectionSecond Darkest Mark Detection

For For Erasure AnalysisErasure Analysis

Mark Sense (Generic Image Scanners) True OMR (Scantron)

Identifies mark from black and white (bitone) image

True OMR sees marks in grayscale

Allows for Plain Paper Printing

Marks are either Black (present) or White (absent) based on a single threshold.

Allows for Plain Paper Printing

Darkness of the marks is used to intelligently and accurately distinguish an erasure from an intended mark (mark discrimination).

Many erasures will read as jet black marks.

True OMR can accurately identify a mark as being light, dark, or an erasure.

Useful for low stakes data collection, such as surveys, where picking up some erasures as marks does not significantly affect the survey outcome.

Useful for all data collection when accuracy matters.

Poor choice for most testing due to the inability to determine darkest mark or light marks. Close to 100% accuracy can only be achieved with time consuming manual verification of original documents, which can introduce human error.

True OMR is the standard for the high-stakes testing industry with an accuracy of 99.9997%, without manual verification. If the results from a test are important, shouldn’t they be accurate?

How Mark Sense Sees the World

• Black and White only. No shades of gray.• Loss of detail.• Loss of accuracy when reading data

Mark Sense Black and White Image

• Bitone. Only Black and White.

• Cannot tell the difference between an erasure and an intended mark.

• Mark Sense loss of detail causes multiple marks when erasures are intended.

• Mark Sense is a poor choice for high stakes testing.

Can you tell which are the intended marks? The answers will be shown 2 slides from now.

Mark Sense Read Bi-Tone Original

Reads Bubble 5

Omit

Scanner Normal Threshold

Mark Sense Read Bi-Tone Original

Multiple

Reads Bubble 3

Scanner Low Threshold

How Mark Sense Sees the World

• Black and White only. No shades of gray.• Loss of detail.• Loss of accuracy when reading data

How True OMR Sees the World

• Grayscale. Black, White, and various shades of gray in between.• Increase in detail.• Increase in accuracy when reading data.

True OMR Grayscale

• true OMR has 16 level grayscale read.

• true OMR can accurately tell the difference between an erasure and an intended mark.

• true OMR’s increase in detail causes increase in read accuracy.

• true OMR is ideal for high stakes testing.

Mark Sense OMR

Correct Responses:

D

E

D

Mark sense would have read: mult, C, mult, A, mult, for 3 wrong reads.

OMR would have read: D, C, E, A, D for 5 accurate reads.

What About Light Marks?

Marks that are light can be dropped out by bitone mark sense, and considered to be omits. Because the image will not show light marks, the actual student sheet must be retrieved for visual inspection and correction.

Because True OMR sees in grayscale, light marks will still be read as valid marks, with no user verification required.

Original Mark as seen on sheet

Bitone Mark Sense Reads as Omit

true OMR Reads a Valid Mark

[L]ight setting

[N]ormal setting

[D]ark setting

Paper

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

A B C D E F

True OMR 16 Level ReadMark Threshold (user adjustable)

* Every bubble on the form gets assigned a value from 0 through F (0 – 15)

True OMR 16 Level ReadMark Discrimination Summary

If two or more valid marks are present:

• They must be 3 levels apart or a multiple is recorded

• If both marks are at or above the discrimination cutoff, then there was no attempt at an erasure, and a multiple is recorded.

Mark Threshold, Mark Discrimination, and Mark Discrimination Cutoff are all user definable.

True OMR Second Darkest Mark Read

Returns up to 3 fields:

• Darkest Mark Field – D,B,C,D,E• Second Darkest Mark – A, -,E, - ,B• Optional Darkness Zone - 600E00F00000F08000C00600B

D,B,C,D,E,A,-,E,-,B,600E00F00000F08000C00600B,

Formatted Output :

Darkest Marks

Second Darkest Marks

Darkness Zone information (optional)

Dashes indicate omits

Scantron’s real-time data recognition (True OMR) allows for detection of error conditions during scanning

Generic Image Scanners

Skewed document - Can cause marks to be missed or misinterpreted No

Missing critical data – Scanning can automatically stop if required data is missing such as an ID number or a signature

No

Folded corners covering data – Ensures data under the fold isn’t missed

No

Multiple sheet feeds - Detects when 2 sheets stick together and are scanned at the same time. Prevents loss of data – missing students

Sometimes

Scantron’s scanners are engineered for data capture applications

Generic Image Scanners

Scantron scanners are engineered to read consistently from scanner–to-scanner and form-to-form.

Consistency generally not a design priority.

Scantron scanners with printers are designed to be interactive. They can print information like test scores and error messages on a form based on what was read from that form.

Printers are only available on more costly models. Limited, pre-determined information (if any) like a sequence number and or date. Not interactive - error messages and test scores cannot be printed on a form.

Scantron can determine the second darkest mark.

Cannot determine darkest or second darkest mark.

True OMR Verification• Because true OMR can distinguish between an intended mark and

an erasure, and is capable of reading light marks as well, manual verification of data is not required.

– Saves time– Reduces the chances of human error

• True OMR can still be verified if desired.