Document created by hd0052032 on May 13, 2016Last modified by ruth.neighbors on Dec 22, 2017
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An instructor posed this question to me recently:

"The total weighted grade in Blackboard is different than the grade I calculate by hand. Sometimes it's higher, and sometimes it's lower, so there is no consistency.

I checked the categories and their weights, and they are correct. I tend to round up to the thousandth when I do my hand calculations. I could understand if BB was consistently lower than my calcs or consistently higher, but it's so varied.

Anyway, is there a reason why this is?"

I verified that all columns were included in their specified categories, the columns within each category were to be weighted equally, only one GC column had points awarded in excess of the possible points for that item (this 3 point overage was counted as extra credit/bonus by the instructor), no grades had been entered as a Letter (which Bb would calc at the median for the given letter grade) and worked out a few sample weighted totals from her course and arrived at the same figures as the instructor.

Please see attached example of points earned with Bb weighted total and hand calculated totals - does anyone know how Bb is figuring these weighted totals?

Any thoughts/feedback are appreciated.

Thanks,

Jessica

Can you post the calculations you're making by hand?

What do your actual calculations look like?

The "points per category" is not a relevant number to look at, since it does not really figure at all in weighted total calculations when the columns in each category are weighted equally.

If the columns in a category are weighted equally, that means that each column is first converted to a percentage (because the idea behind weighting the columns equally is that they might all be worth different points possible, and you want that to be irrelevant to the calculations).  Then, the percentages are added up and divided by  the number of columns, to arrive at the percent correct for that category.

Then, you take the percentages for each category and multiply them by the weight for that category.

So, for Student 1, the calculations would look like:

Category A : ((10/10) + (10/10) + (10/10) + (10/10) + (10/10) + (10/10)) / 6 = 1.00  (i.e. 100%)

Category D: (26/28) /1 = .9286

Category S: ((39/45) + (49.5/55) + (74/100) + (86.5/100) + (86.5/100) + (0/100)) / 6 = (.8667 + .9 + .74 + .865 + .865 + 0) / 6 = .7061

Category T: ((42.5/60) + (21/40)) / 2 = (.7083 + .525) / 2 = .6167

Weighted Total: (1.0 x .10) + (.9286 x .15) + (.7061 x .55) + (.6167 x .20) = .1 + .1393 + 3884 + .1233 = .751 (i.e. 75.1%)

Mike

PS:  From your spreadsheet, my guess is that you are using the calculations for proportional weighting of columns in each category. If you try switching the weighted total to use proportional weighing in each category, Blackboard will probably give you the numbers you're expecting...

THANK YOU!  Can you tell it's the end of a VERY long semester ...  I was working through this on Friday last week and apparently didn't contemplate the idea of proportional vs. equal.  This is what happens when 2 english/arts minded ladies do math, I guess.

thanks again, j

Not to worry--I've had to run through these calculations with Engineering/CS folks, too!

One more thing to consider. If you have Running Total set to YES - and you have not forcibly entered a zero for a non entry by a student - the calculations will result differently as well. Setting the Running Total to NO - will automatically put in the assumption of zero for a non entry by a student.

Wow, Impressive work there. I have struggled for a long time making my numbers come out correctly. Finally, I made every single assignment worth 100 pts. I then made categories (or used ones already set up), and assigned weights.  I chose the Weight columns  equally

I ended up with a nice set up which actually manages my grade book values. Of course every grade fits into one of these categories, and I set up each column in the grade book with one of these categories. Some of the percents, like the essays and exams are set by our department, and I split the rest of the points for Discussion Boards and "small" assignments like Blogs, etc. L. Ward Category:     Midterm Exam  (example 20 percent)

:

Weight Columns:

Drop
Drop

OR Category:     Discussion Forums     (14 percent)

:

Weight Columns:

Drop
Drop

OR Category:     Final Exam Essay     (20 percent)

:

Weight Columns:           checked

Drop
Drop

OR Category:     Assignment-Small     (1 percent)

:

Weight Columns:            Checked

Drop
Drop

OR

:

Weight Columns:

Drop
Drop

OR

:

Weight Columns:

Drop
Drop

OR

Total Weight:                     100%

•           Calculate as Running Total     Yes
Calculate as Running Total

That one seems to get some of our students (& teachers) in a jam every semester,  I have an appointment this summer to help an instructor restructure her gradebook to hopefully eliminate the, "What do you mean I got an 'F', I have 76%!" messages at the end of the term due to this exact issue.

Thanks for the note,

Jessica

Thanks Laviece, I think some of our instructors may prefer this set up and I'm sure the students like having all assignments initially graded on a 100 point scale.

- Jessica

This document was generated from the following discussion: Weighted Grade Calculations

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