What to bloody write for validity, reliability and accuracy?? (1 Viewer)

[get_back23]

these questions come up often, but i never know what to write,

Yes i know the definitions for the 3 words but they dont help jackshit


E.g. reliability means the consistency of the results
Q: how can student ensure reliability in ...
all i know is repeat the experiment 3 times, which i doubt can even get me a mark

Also irkn reliability and accuracy is so similar in terms of what we do
E.g. for sulfate fertiliser quantitative analysis,
for relibiability, we wash the precipitate to rid of solutes and adhering particles, and then dry it right?
Its the bloody same for accuracy then coz washing adhering particles and drying means its closer to the actual weight each time, which is accuracy?

helppp me!! lol

 

[madharris]

Reliability: the ability to repeat the experiment several times and achieve similar results
Accuracy: the result achieved or observation is close to the textbook or accepted value
Validity: how 'good' the experiment is e.g. if you use scales to weigh the height of someone then the experiment is not valid

 

[someth1ng]

Reliability: the experiment was repeated and results were compared with the class, the results were acceptably consistent and hence, the experiment was valid.

Validity: the experimental method correctly and theoretically answered the aim however this relied each step of the process to be ideal.
Although it appears to be valid, the actual experiment was invalid because:
- Some BaSO4 could adhere to the walls of the sintered glass funnel
- Some BaSO4 would pass through the filtration as their crystals are extremely small
- Some BaSO4 did not precipitate out of solution as the fertiliser
- Even though BaSO4 is considered insoluble, very small amounts can still dissolve in water, especially when heated and hence, it would not be fully filtered.
- Excess BaCl was needed or only some of the BaSO4 would precipitate out
- Some insolubles that could have contained sulfates
- When using filter paper, some of the liquid solution went on the outside of the paper, by passing filtration completely. This caused some BaSO4 to not undergo filtration.
- When the filter paper was "dry", it may still contain some water, adding to the original mass.

Accuracy
- The experiment was invalid due to the above reasons, this caused the accuracy to be unreliable as so many variable could have changed the actual value significantly
- Therefore, the experiment was not accurate.