3 ms·

If you are doing any sort of data analysis you really need to avoid spreadsheets. Unfortunately, most data analysis is just as bad. I have worked with SAS & R

by trapper 18y ago

If you are doing any sort of data analysis you really need to avoid spreadsheets. Unfortunately, most data analysis is just as bad. I have worked with SAS & R code, thousands of lines long, all without a single test. Basically a big series of hacks. Mostly, statisticians I have worked with have no concept of testing, or even why it's necessary. I shudder to think of the gross error in research results from all I have seen!

adsyoung 18y ago
Yeah...we do most aircraft structural analysis in excel. It scares the hell out of me.
- trapper 18y ago
  That is just scary.
  - adsyoung 18y ago
    Well the thing to remember is that everything is checked twice and there's a 1.5 safety factor on top to protect against mistakes but the state of the industry is poor. Engineers often get away with creating monstrous spreadsheets that are difficult to follow: - scattered logic - methodology obsficated with complex excel formulas - magic numbers that you have a hell of a time tracking down the source of - links all over the place. Are they still valid or have they gone bad due to all the copy/pasting? etc etc As a programmer who has to write something that has logic and no ambiguity for a computer to understand it, it makes you want to beat your head against a wall trying to understand and check someones work. Until recently (victim of the downturn) I was in a small dev team looking to automate and improve things. We had some good wins but it's a struggle. If someone like toyota starts making aircraft seriously and develops more standardized methods rather than simply employing piles of engineers to punch numbers wildly into excel they may be able to crush everyone else in time to market.
    - gruseom 18y ago
      magic numbers that you have a hell of a time tracking down the source of - links all over the place. Are they still valid or have they gone bad due to all the copy/pasting? etc etc Would it help to have a sheet of centralized assumptions (constants, magic numbers, etc.) that people could link to from any spreadsheet? Would it help to be able to reuse formulas from another sheet without copy/pasting them? i.e. link in such a way that you can fill in your own numbers, but keep the original logic? Would it help to be able to "lock down" certain models that people could use to do their analysis, but not make arbitrary changes to? Would it help to be able to build some computations in a spreadsheet and wrap them up as a function that other spreadsheets could call (passing in their own arguments)? I'm interested in what can be done to raise the level of abstraction (and consistency) without giving up the spreadsheet UI which is so productive for many users.
      - adsyoung 18y ago
        Yes to all of those and that's part of what we try and do. There are also many models/ideas from programming that are applicable to the way engineering should be done I feel, such as don't repeat yourself, reducing dependencies etc There are software tools for analysis developed to standardise what can be standardised and to force people to use templates for their analysis, but they are generally not great and getting them developed is always politically and financially challenging. IMHO engineers find it difficult to identify and extract the common processes because every part is slightly different and complex and usually requires its own judgement calls to be made about how to deal with it. This leads naturally to everyone doing things their own way and therefore using the most flexible and cheap tool there is...Excel. That's not to say there aren't common processes and higher abstractions to be made, it just requires people to look hard for them and think about things in a way that does not come naturally to the industry. They also need to have the clout to get people using them. I think things are changing some what with modern aircraft though. My opinion is that judgement is playing less of a role in many cases and we are moving to brute force analysis i.e. Just throw it at the computer and analyse it all in great detail. This leads to more common processes and standard ways of sharing and moving data around. It's a big problem and I enjoy working on it but the support isn't always there to invest in it. The cost of designing an aircraft is tiny compared to the overall lifecycle of the aircraft and the costs involved in manufacturing. So the industry would generally prefer to keep operating in the same old ways rather than take risks on new things. Especially new things that involve upfront investment. Just my opinion anyway.
time_management 18y ago
Trying to do real programming in SAS is a nightmare. The language sucks. Also, it's proprietary and expensive. It's surprising that statisticians would fail to understand the importance of testing, given that a lot of the root issues in statistics (e.g. the Bayesian/frequentist dispute over "what is a probability?") are epistemological.
- trapper 18y ago
  Agreed entirely. I don't understand why they don't get testing either. Not one I have met realises just how error ridden their scripts probably are. Still, a lot of programmers don't understand the value of testing yet.
- thwarted 18y ago
  One of my undergrad classes was for SAS, and they mixed MIS, CS, math, and statistics people in this class. It took weeks for those on the CS track to get that when your code says "proc average", you're _calling_ a procedure, not defining a function. We had no idea where the code was supposed to go. There was a serious disconnect between the students and the professor in that class, who, I later realized would have just needed to say "this calls the procedure average" and things would have been fine. We had no idea, initially, how we were getting results. Of course, we had to run all this on VMS and print it out on a fan-fold line printer, and it wasn't very interactive. SAS products seem to be more visual and interactive now.

by trapper 18y ago

adsyoung 18y ago

Yeah...we do most aircraft structural analysis in excel. It scares the hell out of me.

trapper 18y ago
That is just scary.
- adsyoung 18y ago
  Well the thing to remember is that everything is checked twice and there's a 1.5 safety factor on top to protect against mistakes but the state of the industry is poor. Engineers often get away with creating monstrous spreadsheets that are difficult to follow: - scattered logic - methodology obsficated with complex excel formulas - magic numbers that you have a hell of a time tracking down the source of - links all over the place. Are they still valid or have they gone bad due to all the copy/pasting? etc etc As a programmer who has to write something that has logic and no ambiguity for a computer to understand it, it makes you want to beat your head against a wall trying to understand and check someones work. Until recently (victim of the downturn) I was in a small dev team looking to automate and improve things. We had some good wins but it's a struggle. If someone like toyota starts making aircraft seriously and develops more standardized methods rather than simply employing piles of engineers to punch numbers wildly into excel they may be able to crush everyone else in time to market.
  - gruseom 18y ago
    magic numbers that you have a hell of a time tracking down the source of - links all over the place. Are they still valid or have they gone bad due to all the copy/pasting? etc etc Would it help to have a sheet of centralized assumptions (constants, magic numbers, etc.) that people could link to from any spreadsheet? Would it help to be able to reuse formulas from another sheet without copy/pasting them? i.e. link in such a way that you can fill in your own numbers, but keep the original logic? Would it help to be able to "lock down" certain models that people could use to do their analysis, but not make arbitrary changes to? Would it help to be able to build some computations in a spreadsheet and wrap them up as a function that other spreadsheets could call (passing in their own arguments)? I'm interested in what can be done to raise the level of abstraction (and consistency) without giving up the spreadsheet UI which is so productive for many users.
    - adsyoung 18y ago
      Yes to all of those and that's part of what we try and do. There are also many models/ideas from programming that are applicable to the way engineering should be done I feel, such as don't repeat yourself, reducing dependencies etc There are software tools for analysis developed to standardise what can be standardised and to force people to use templates for their analysis, but they are generally not great and getting them developed is always politically and financially challenging. IMHO engineers find it difficult to identify and extract the common processes because every part is slightly different and complex and usually requires its own judgement calls to be made about how to deal with it. This leads naturally to everyone doing things their own way and therefore using the most flexible and cheap tool there is...Excel. That's not to say there aren't common processes and higher abstractions to be made, it just requires people to look hard for them and think about things in a way that does not come naturally to the industry. They also need to have the clout to get people using them. I think things are changing some what with modern aircraft though. My opinion is that judgement is playing less of a role in many cases and we are moving to brute force analysis i.e. Just throw it at the computer and analyse it all in great detail. This leads to more common processes and standard ways of sharing and moving data around. It's a big problem and I enjoy working on it but the support isn't always there to invest in it. The cost of designing an aircraft is tiny compared to the overall lifecycle of the aircraft and the costs involved in manufacturing. So the industry would generally prefer to keep operating in the same old ways rather than take risks on new things. Especially new things that involve upfront investment. Just my opinion anyway.

time_management 18y ago

Trying to do real programming in SAS is a nightmare. The language sucks. Also, it's proprietary and expensive. It's surprising that statisticians would fail to understand the importance of testing, given that a lot of the root issues in statistics (e.g. the Bayesian/frequentist dispute over "what is a probability?") are epistemological.

trapper 18y ago
Agreed entirely. I don't understand why they don't get testing either. Not one I have met realises just how error ridden their scripts probably are. Still, a lot of programmers don't understand the value of testing yet.
thwarted 18y ago
One of my undergrad classes was for SAS, and they mixed MIS, CS, math, and statistics people in this class. It took weeks for those on the CS track to get that when your code says "proc average", you're _calling_ a procedure, not defining a function. We had no idea where the code was supposed to go. There was a serious disconnect between the students and the professor in that class, who, I later realized would have just needed to say "this calls the procedure average" and things would have been fine. We had no idea, initially, how we were getting results. Of course, we had to run all this on VMS and print it out on a fan-fold line printer, and it wasn't very interactive. SAS products seem to be more visual and interactive now.