GPU Benchmarking Methods Investigated: Fact vs. Fiction

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Originally Posted by iMacmatician

I've been wondering why reviews haven't been using the standard deviation.

Cos then we'd ask for confidence intervals and more hard stats.

Quote:

Originally Posted by cegras

bamtan: Yeah, but to get an accurate average you need at least 5 runs. And that's just for a making sure you have a good linear fit. The sample size for statistically relevant average + 3 SD rule would be LARGE.

Extrapolating from 3 runs gives you no useful information at all.

shrug, I don't think I mentioned how many runs should be done

but since you brought it up, I disagree with you because I don't think computer game benchmarks vary enough that "3 runs gives you no useful information at all"

I'm trying to help because every video card review on the web is at a grade 6 mathematics level. you are too, but you just landed a bridge too far

Quote:

Originally Posted by SKYMTL

Like I said in the conclusion: there is no "right" way to go about it. Kyle's team has a unique persepctive and it sets them (and sometimes their conlcusions) apart from the norm. They do use in-game sequences and research things properly it seems which is a huge step in the right direction. However, I am not actually sure if they include action sequences in their benchmarks or if they are just doing a run-through.

What the article is really meant to convey is that the vast majority of standard benchmarking methods (built in benchmarks & stand-alone) are dead wrong. This is why readers should push for a transparent benchmarking process where there is disclosure of exactly which methods were used.

I can't speak for other sites but the fact that we test every run three times and average out the results eliminates any "zingers" when it comes to minimum framerates. Average FPS are also there for a reason. :up:

I fully plan to include my testing methodology whenever i start up a new review... explaining the software and the environments used. Otherwise, i'm just putting the cloth over my readers' eyes. :p:

My point of view is that games are very finnicky and the most important thing is not scores or anything like that, its all about raw performance in games and the best bang for your bucks as well as the best performance money can buy. I don't care what company is better or worse, I just want to give my readers a clear cut and well informed as well as transparent review.

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Originally Posted by hurleybird

The ironic thing here is that this article is perpetuating one of the most common benchmarking mistakes of today: providing minimum frame rates without qualifying them. Minimum FPS by itself is worthless, since for all you know it be for a single frame at the start of the level, or conversely that card might be hitting that minimum frame-rate all of that time. Another example, if one card hits a very low minimum frame rate once for a very short period, and another card hits a higher minimum frame rate but goes there more often, it's the first card with the lower min fps that is providing the better game play experience. If you want to provide minimum frame-rates, you MUST qualify them with a graph of fps over time, or at the very least a description of the gameplay. Unfortunately this poor methodology is very widespread.

I think you are right, the solution by my estimate is to provide data on the MEDIAN of FPS, as this will tell you with average and minimum FPS where the range lies the most.

Quote:

Originally Posted by bamtan2

I'm trying to help because every video card review on the web is at a grade 6 mathematics level. you are too, but you just landed a bridge too far

just right for many of the readers then. i'm sure less than 1% of readers of a typical vga review understand what standard deviation is, people have difficulties "reading" linear x-y plots

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Originally Posted by W1zzard

just right for many of the readers then. i'm sure less than 1% of readers of a typical vga review understand what standard deviation is, people have difficulties "reading" linear x-y plots

+1.

People don't want to sit there for 2 minutes looking at linear graphs and charts. They want to see the result and see it quick. :yepp:

Quote:

Originally Posted by Stukov

I think you are right, the solution by my estimate is to provide data on the MEDIAN of FPS, as this will tell you with average and minimum FPS where the range lies the most.

You do know what median means right? Middle. Median of what? Median of FPS? What? The Mode is the most. :shrug:

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Originally Posted by BeepBeep2

+1.

People don't want to sit there for 2 minutes looking at linear graphs and charts. They want to see the result and see it quick. :yepp:

You do know what median means right? Middle. Median of what? Median of FPS? What? The Mode is the most. :shrug:

http://en.wikipedia.org/wiki/Median

Median is the "middle" of a series of numbers. So if you have 1, 1, 1, 2, 3, 4, 5...2 is the median number. Having the Median number would allow you to know on which side of the average you will get most of the time. Average mean can be heavily skewed by massive jumps in data (or FPS here) or massive drops.

Let's say its 1, 1, 1, 2, 3, 100 the average mean would be 18, however the mean would 1-2 (1.5). In terms of FPS, if you have a lot of an average of 60, a minimum of 20, and a median of 65 will tell you that getting 20 FPS is not very likely, but if the median was 30, it would tell you that you end up lower than 60 quite often, but there are some high peaks skewing it higher.

Quote:

Originally Posted by W1zzard

just right for many of the readers then. i'm sure less than 1% of readers of a typical vga review understand what standard deviation is, people have difficulties "reading" linear x-y plots

readers don't need to know what it is. it is just a tool to produce a result. like adding and dividing produces average, standard deviation can produce a useful minimum

Quote:

Originally Posted by Stukov

http://en.wikipedia.org/wiki/Median

Median is the "middle" of a series of numbers. So if you have 1, 1, 1, 2, 3, 4, 5...2 is the median number. Having the Median number would allow you to know on which side of the average you will get most of the time. Average mean can be heavily skewed by massive jumps in data (or FPS here) or massive drops.

Let's say its 1, 1, 1, 2, 3, 100 the average mean would be 18, however the mean would 1-2 (1.5). In terms of FPS, if you have a lot of an average of 60, a minimum of 20, and a median of 65 will tell you that getting 20 FPS is not very likely, but if the median was 30, it would tell you that you end up lower than 60 quite often, but there are some high peaks skewing it higher.

the biggest problem with median is the fluctuation of fps is very noticable. if your talking about mpg, you dont really care if one tank gets 20 and the next gets 30, and then back to 20, but in games thats called micro stuttering, lol, and people really hated that.

i think line graphs is where its at, 100%. anything else takes away from that. sure you can have summaries, but the raw data needs to be fully available for some readers who do take the time to read.

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Originally Posted by Manicdan

im pretty sure older cards are still better price/perf kings, considering a 4850 is 100$, nearly 1/3 the price, but i doubt its 3x slower

Yeah but it runs 3x hotter and it's not really faster than even, cheaper, smaller 8800GT.

5850 is the best price/performance card especially when clocked to 1000Mhz core.

Quote:

Originally Posted by QuadDamage

Yeah but it runs 3x hotter and it's not really faster than even, cheaper, smaller 8800GT.

5850 is the best price/performance card especially when clocked to 1000Mhz core.

when you speak in absolutes it takes only one counterexample to disprove you.

we are way off topic here, but you must be corrected. used cards have huge discounts, making it very difficult for any new card to compete for the price/performance crown.

example: gtx 260 goes for $120 on ebay. 5850 is about $300. 5850 is not near twice as fast as gtx 260.

http://completed.shop.ebay.com/i.htm...c0.m283&_rdc=1

http://www.guru3d.com/article/vga-ch...ecember-2009/4

2 Attachment(s)

you could display the spread of framerates like in the 1st attached pic, where the green GPU has higher average and max framerates but doesn't do as well at lower framerates

if you had more FPS ranges on the x axis (eg 30 instead of the 10 in my pic) it could look good as a line graph instead of a bar graph

if you had heaps of FPS ranges on the x axis (eg each fps range was an integer) and just used a colored dot for each value you'd get a cloud of scattered dots that would look good if you had enough data points.

but you'd often want to compare multiple GPUs and multiple resolutions and too many graphs can be a nuisance... but if you made the columns of a multiple GPU/resolution graph into representations of the FPS spread (eg the "red" GPU that i did for example's sake in the 2nd pic, where each horizontal line is perhaps a integer FPS value, and its width represents how much time the GPU spends at that FPS, i didn't bother mspainting the other bars to perfection) you could display the full story in a single JPG

Quote:

Originally Posted by W1zzard

just right for many of the readers then. i'm sure less than 1% of readers of a typical vga review understand what standard deviation is, people have difficulties "reading" linear x-y plots

implicitly they can understand it. kind of like how you understand physics and use it in every day life even though you dont solve PDE's in your head.

as shown above anyone can see the distribution of framerates and see that card X has more consistent framerates than card Y. if they dont know what to look for tell them or explain it.

btw im not a fan of typical reviews. sites should do something unique, something that gives them individuality and a reason to visit them. as a technical person i would like to see in depth statistical analysis of benchmarks.

http://www.xtremesystems.org/forums/...1&d=1277059023

a good point is made here, which is that just changing the presentation (what Y and X represent) of existing data can change how useful the picture is.

normal reviews have Y=framerates along the left, and X=time along the bottom. but wait a second, who cares about time? we don't even know what the benchmark was doing at any given time.

so rather than a graph presenting what speed things were going at a given time, why not use the exact same data to present how often things were going a given speed?

This here is the good :banana::banana::banana::banana:.

Here's what I do with vbscript based off of samples provided (la as a 2d array) to calculate "average" (median) fps. Comments/Criticism very welcome. :woot:

Code:

i="0" Select Case UBound(la) Case "1" avgfps=la(1) WScript.Echo "Average FPS=" & avgfps Case "2" for i = 1 to ubound(la) sum=sum + la(i) Next avgfps=sum/ubound(la) WScript.Echo "Average FPS=" & avgfps Case "3" for i = 1 to ubound(la) If sDebug=1 Then WScript.Echo "la(" & i & ")=" & la(i) If la(i)>la(high) Then high=i If la(i)<la(low) Then low=i Next for i = 1 to ubound(la) Select Case i Case high If sDebug=1 Then WScript.Echo "la(" & i & ") is high!" ' throw it away! Case low If sDebug=1 Then WScript.Echo "la(" & i & ") is low!" ' throw it away! Case Else avgfps=la(i) End Select Next WScript.Echo "Average FPS=" & avgfps Case "4" for i = 1 to ubound(la) If sDebug=1 Then WScript.Echo "la(" & i & ")=" & la(i) If la(i)>la(high) Then high=i If la(i)<la(low) Then low=i Next for i = 1 to ubound(la) Select Case i Case high If sDebug=1 Then WScript.Echo "la(" & i & ") is high!" ' throw it away! Case low If sDebug=1 Then WScript.Echo "la(" & i & ") is low!" ' throw it away! Case Else avgfps=avgfps + la(i) If sDebug=1 Then WScript.Echo "la(" & i & ") one of our sweet values!" ' throw it away! End select Next If low=high Then avgfps=avgfps/3 If sDebug=1 Then WScript.Echo "avgfps=(3)" & avgfps Else avgfps=avgfps/2 If sDebug=1 Then WScript.Echo "avgfps(2)=" & avgfps End If WScript.Echo "Average FPS=" & avgfps Case "5" for i = 1 to ubound(la) WScript.Echo "la(" & i & ")=" & la(i) If la(i)>la(high) Then high=i If la(i)<la(low) Then low=i Next for i = 1 to ubound(la) Select Case i Case high WScript.Echo "la(" & i & ") is high!" ' throw it away! Case low WScript.Echo "la(" & i & ") is low!" ' throw it away! Case Else avgfps=avgfps + la(i) WScript.Echo "la(" & i & ") one of our sweet values!" ' throw it away! End select Next If low=high Then avgfps=avgfps/4 WScript.Echo "avgfps=(3)" & avgfps ' throw it away! Else avgfps=avgfps/3 WScript.Echo "avgfps(2)=" & avgfps ' throw it away! End If WScript.Echo "Average FPS=" & avgfps Case Else for i = 1 to ubound(la) WScript.Echo "la(" & i & ")=" & la(i) If la(i)>la(high) Then high=i If la(i)<la(low) Then low=i Next for i = 1 to ubound(la) Select Case i Case high WScript.Echo "la(" & i & ") is high!" ' throw it away! Case low WScript.Echo "la(" & i & ") is low!" ' throw it away! Case Else avgfps=avgfps + la(i) WScript.Echo "la(" & i & ") one of our sweet values!" ' throw it away! End select Next If low=high Then avgfps=avgfps/(ubound(la)-1) WScript.Echo "avgfps=(3)" & avgfps ' throw it away! Else avgfps=avgfps/(ubound(la)-2) WScript.Echo "avgfps(2)=" & avgfps ' throw it away! End If WScript.Echo "Average FPS=" & avgfps End Select avgfps=Round(avgfps,2) logfile.WriteLine ("AVERAGE FPS: " & avgfps)

Interesting but how would you do that in a program like Excel in a quick and easy manner? I am guessing you could make a Custom List but that would take an insane amount of time. (directed @ Batman)

Also, NVIDIA's newest WHQL drivers pretty much bring my point about in-game benchmarks into pretty sharp focus. They are claiming a massive framerate jump in the Concrete Jungle benchmark. In game? Nadda.

Quote:

Originally Posted by W1zzard

just right for many of the readers then. i'm sure less than 1% of readers of a typical vga review understand what standard deviation is, people have difficulties "reading" linear x-y plots

Hey W1z; first of all, I'm a HUGE fan of your work. Thank you for all your contributions to the community. Just wanted to say that I think we're selling ourselves short. I would assert that the number is closer to 20%, but we look at it as a much smaller minority because that minority tends not to be very "vocal" in the first place. If someone gets it, they rarely complain; they just consume and move on.

To that end, I think there is an audience for more intelligent data, it's just an audience that is difficult to market to or convince to do much of anything through standard advertising means.

nice article... :toast:

Nice read :up:

One observation though - when it comes to actual performance in a game, there is a difference between stand-alone benchmarks and different portions of the game, thus sustaining your point. However, when it comes to the % diference of performance between 5850 and GTX 470 (your examples) I see almost not percentage difference between the two from one situation to the other.

The point is very simple, based on your tests and results - if real-life performance in a game is what you are after, then in-game testing, even if it is far less accurate then benchmarks due to a large number or variables, is the way to go. However, if accurate performance percentage difference between 1,2,3, etc products is what you are after, benchmarks are in no way less representative then in-game testing.

Quote:

Originally Posted by Monstru

The point is very simple, based on your tests and results - if real-life performance in a game is what you are after, then in-game testing, even if it is far less accurate then benchmarks due to a large number or variables, is the way to go. However, if accurate performance percentage difference between 1,2,3, etc products is what you are after, benchmarks are in no way less representative then in-game testing.

You can't forget that we're talking about playability as well. Take the AvP benchmark for example. If you were going by the stand-alone test, you would be under the wrong impression that none of the tested cards could actually play the game.

The same could be said about some in-game benchmarks such as the Desert sequence in Just Cause 2. If you went by that, you would once again get the wrong impression since most cards perform amazingly in it while the game itself is more challenging.

I agree with SKYMTL. Conclusion? We need more horsepower. I'm starting to feel the age of my 4890. Damn source games dipping me to below 30 fps sometimes.