We can use Excel’s LOOKUP function to quickly convert exam or test scores to letter grades like A+ or F. In this article, let me explain the process and necessary formulas. I will also share a technique to calculate letter grades from test scores using percentiles.
Step 1: Set up a Mapping Table for Letter Grade & Scores
In your workbook, set up a mapping (or lookup) table like this to map out each of the letter grades to the test score boundary.
- When setting up the mapping table, make sure to start from lower score to higher score (for ex: 0 to 100)
- For each grade, just specify the lower boundary value. So for example, Grade F begins from 0, Grade B- begins from 65
Step 2: Calculate the letter grades using LOOKUP function
For this you need all the test scores for your students. Let’s say you have the test scores in column C, from cell C4. In an adjacent column, you can calculate the letter grade using the below LOOKUP formula.
=LOOKUP(C4,$G$6:$G$16,$F$6:$F$16)In this formula:
- First value (C4) refers to the score for which you need the letter grade
- Second value ($G$6:$G16) is the “scores from” column of your mapping table set up in Step 1.
- Third value ($F$6:$F$16) is the “letter grade” column of your mapping table.
Once you have a result for the first test score, drag the formula down to see letter grades for all students.
How to get Letter Grades from Percentiles (relative grading)
Sometimes you may want to calculate the letter grade from the percentile of the test score. This sort of thing is also called relative grading (RG). To do this, we can use the PERCENTILERANK functions of Excel.
Here is a 3 Step process for that:
Step 1: Set up a percentile-wise mapping table for letter grades
In your worksheet, set up a mapping table for letter grades like this:
Step 2: Calculate the Percentiles for each test score
Let’s say you have test scores in column C, in the range C4:C43.
In column D, write the formula =PERCENTRANK.INC($C$4:$C$43,C4) to calculate the percentile of test score in first cell against all scores. The result of this would be a percentile from 0% to 100% (both inclusive).
When you get the result for first cell, drag the formula down to fill up the rest.
Tip: If you want to calculate the percentile by excluding 0th and 100th percentiles, use the PERCENTILE.EXC function instead.
Step 3: Convert Percentiles to Letter Grade
For this, we can use the LOOKUP function again. In column E use the below function:
=LOOKUP(D4,$H$6:$H$16,$G$6:$G$16)In the above formula:
- First value (D4) refers to the percentile we calculated in step 2.
- Second value ($H$6:$H16) is the “percentile from” column of your mapping table set up in Step 1.
- Third value ($G$6:$G$16) is the “letter grade” column of your mapping table.
Download Test Score to Letter Grade Calculation Template
I made a quick Excel template to calculate letter grades from your test / exam marks. Just plug-in your values and see the results instantly. Download the template here.
Bonus: These formulas work in Google Sheets too!
That is right. All these formulas will work exactly same with Google sheets too. Here is a Google Sheets template if you need some help.
Things to keep in mind when calculating letter grades
Do take these cautions when calculating alphabetic letter grades from your exam marks.
- Mapping table setup: your letter grade mapping table needs to be from lowest marks / scores to highest. Just specify the lower boundary for each letter grade.
- For example, if grade F is from exam score 0 to 35, then write 0.
- If grade B+ is from 80 to 85, then write 80
- Clean up your data: If your test score data has missing values (for example, absent or hyphens) then the LOOKUP formula will give #N/A error. So clean up your data before you apply the LOOKUP function.
Next steps:
Now that you have calculated the letter grades, you may want to see the distribution of your student grades or understand which students are failing and need help. Use below Excel concepts & resources to do that.
14 Responses to “Group Smaller Slices in Pie Charts to Improve Readability”
I think the virtue of pie charts is precisely that they are difficult to decode. In many contexts, you have to release information but you don't want the relationship between values to jump at your reader. That's when pie charts are most useful.
[...] link Leave a Reply [...]
Chandoo,
millions of ants cannot be mistaken.....There should be a reason why everybody continues using Pie charts, despite what gurus like you or Jon and others say.
one reason could be because we are just used to, so that's what we need to change, the "comfort zone"...
i absolutely agree, since I've been "converted", I just find out that bar charts are clearer, and nicer to the view...
Regards,
Martin
[...] says we can Group Smaller Slices in Pie Charts to Improve Readability. Such a pie has too many labels to fit into a tight space, so you need ro move the labels around [...]
Chandoo -
You ask "Can I use an alternative to pie chart?"
I answer in You Say “Pie”, I Say “Bar”.
This visualization was created because it was easy to print before computers. In this day and age, it should not exist.
I think the 100% Bar Chart is just as useless/unreadable as Pies - we should rename them something like Mama's Strudel Charts - how big a slice would you like, Dear?
My money's with Jon on this topic.
The primary function of any pie chart with more than 2 or 3 data points is to obfuscate. But maybe that is the main purpose, as @Jerome suggests...
@Jerome.. Good point. Also sometimes, there is just no relationship at all.
@Martin... Organized religion is finding it tough to get converts even after 2000+ years of struggle. Jon, Stephen, countless others (and me) are a small army, it would take atleast 5000 more years before pie charts vanish... patience and good to have you here 🙂
@Jon .. very well done sir, very well done.
good points every one...
I've got to throw my vote into Jon's camp (which is also Stephen Few's camp) -- bars just tend to work better. One observation about when we say "what people are used to." There are two distinct groups here (depending on the situation, a person can fall in either one): the person who *creates* the chart and the person who *consumes* the chart. Granted, the consumers are "used to" pie charts. But, it's not like a bar chart is something they would struggle to understand or that would require explanation (like sparklines and bullet graphs). Chart consumers are "used to" consuming whatever is put in front of them. Chart creators, on the other hand, may be "used to" creating pie charts, but that isn't an excuse for them to continue to do so -- many people are used to driving without a seatbelt, leaving lights on in their house needlessly, and forwarding not-all-that-funny anecdotes via email. That doesn't mean the practice shouldn't be discouraged!
[...] example that Chandoo used recently is counting uses of words. Clearly, there are other meanings of “bar” (take bar mitzvah or bar none, for [...]
[…] Grouping smaller slices in pie chart […]
Good article. Is it possible to do that with line charts?
Hi,
Is this available in excel 2013?