The big ugly AAS reliability/validity question (1 Viewer)

[sneeble]

What did you write? Why?

I'd type mine out but I've got to drive my dad somewhere, so I'll post it up when I get back!

 

[~*HSC 4 life*~]

which question?

there was two i can remember on the top of my head

lamp/flame

and validty...die validity!

 

[Plebeian]

Reliability
+ for performing multiple analysis
- for not discarding the 0.64 result

Validity
+ AAS a suitable technique
- only using one sample of soil

I don't know how correct that is though.

 

[Kazuya]

that's all i did

 

[stevenwong86]

I wrote it was good, but it could have been improved by:

-collecting more samples
-using a graph and line of best fit instead of taking the average

 

[ay_caramba]

ok not too confident abt this one
Validity:
* AAS generally an accurate technique, would be valid if AAS had been accurately calibrated beforehand--argh
* validity would be undermined if standard solutions used were contaminated- okay thats a load of crap
Reliability:
* multiple tests were performed
* majority of results were of a similar value.. except the 0.64 one


oh dear.

 

[Narelle]

Reliability
+ for performing multiple analysis
- for not discarding the 0.64 result

Validity
+ AAS a suitable technique
- only using one sample of soil

I don't know how correct that is though.

Indeed... I concur

 

[euphoric]

nooo.
i didnt mention about discarding 0.64 ><

 

[Managore]

Dammit I forgot to give the positives.. I said it more samples, disregarding 0.64 and doing more decimal places for further accuracy...

 

[Komaticom]

Bah!
I just picked an element with valence 3+ and said it forms a precipitate.
Bah! I'm screwed.

 

[aim54x]

Reliability
+ for performing multiple analysis
- for not discarding the 0.64 result

Validity
+ AAS a suitable technique
- only using one sample of soil
.

i wrote d same xcept i didn't mention more samples.
technique correct
concentration unreliable cause the inclusion of the outlier

 

[The Bograt]

I said anything I could think of:
-get more samples
-samples in different places, especially near possible sources of mercury
-valid in that they used an 'approved' method
-exclude 0.64 result
-valid in that they tested same sample multiple times
-AAS is bloody accurate
-I gave the new average without 0.64

Reckon it would have been worth saying do tests at different depths?

 

[googleplex]

What I got from the question:

The sample was taken from one site; 5 lots of AAS tests done on that sample. Soil is a not a homogenous mixture so obviously you could get different amounts of mercury if you split a sample of soil into five tests.

So why would you discard the 0.6 reading - AAS is extremely accurate, e.g 0.01ppm, so why would it produce discrepant results UNLESS the method was flawed.

 

[Steven12]

far out, i knew i screwed this question cos i said it wasnt a really reliable test as soil particles can get in the way of the experiment(cant believe i said that), and i also said the average absorbance wasnt reliable cos 0.64 was far out, therefore the average absorbance is also incorrect.

man, i think this question was out of 5. i get for 2 it if am lucky, far out and i had such high expectation of this exam, arrrrrrrrrrrrrrrrr why wont put more theory into this exam?

 

[sneeble]

Hrrm...

I said the validity was flawed due to the fact they only tested one sample. I said samples from different depths/areas needed to be taken, as one sample doesn't accurately test the hypothesis.

I said the reliability was flawed also, seeing as the same sample tested 5 times came up with different results; inconsistent results from 1 sample space = unreliable, IMHO. There is no point in splitting one sample into 5 tests and averaging the result of all the tests, I don't think that's what they meant.

 

[sub]

crap i forgot to mention something about the aas technique ...everything else i got

 

[xeriphic]

I only put

valid
* AAS accurate in small concentrations

reliable
* repeated
* more sources for mercury samples from near site

 

[scruffy012]

yeah i think i put that they needed mre sites, and that thwey didnt discard the 0.64, i did some other, but i dunno

 

[rogersla]

I said that the method in theory is reliable but big left-field values (such as the .64 one) can ruin the validity. Of course much more eloquently.

 

[lucyinthehole]

i put something like
AAS = appropriate technique
reliability good for 1,2,3 and 5 (within 2 ppm variation wan't it?)
4 should've been discarded
since it wasn't, validity kinda scrwed up