# Thread: Reliability, validity and accuracy: What's the difference.

1. ## Reliability, validity and accuracy: What's the difference.

This is probably something that's covered in year 10 at the very latest but I'm still confused. Explain please?

2. ## Re: Reliability, validity and accuracy: What's the difference.

The above is a link to an actual article released by Curriculum Support in science, for education.

With regard to accuracy, it is simple how close your experimental data is to the actual results.

3. ## Re: Reliability, validity and accuracy: What's the difference.

Reliability is the consistency of your results and can be improved by repeated the experiment and increasing sample space for the experiment and taking the avg or results
Accuracy usually concerns the measurments - have you used the correct and most precise and appropriate measuring equipment? (e.g. measure with a measuring cylinder rather than say..a beaker)
Validity...im not really sure on this, but i think its whether the results you obtained or the experiment as whole provided a valid conclusion which tested the hypothesis and satisfied the aim.

At least thats what we're told at my school, ofc this is all from the top of my head, so check up on it - they will usually ask u how to improve these aspects.

Good luck

4. ## Re: Reliability, validity and accuracy: What's the difference.

Blushii is right.

I'd like to further emphasise the concept of "validity". Validity can be referred to your actual methods - which means "is this the right method to use to measure this?".

Validity can also be referred to your conclusion - meaning "from what you have found (your results), have you made an approrpiate conclusion based on what you've got?" For example, if you observed 10 trees with blue leaves (results) and you claim that all trees have blue leaves (conclusion), this is an invalid conclusion. Similarly, if you have tested 100 cows with disease ABC and 100 healthy cows, and you've found that all 100 cows with disease ABC have the E. coli bacterium and none in the healthy cows, and you conlcuded that E. coli is associated with disease ABC, this is a valid conclusion.

I hope this helps!

5. ## Re: Reliability, validity and accuracy: What's the difference.

sophisticated-, have you cleared up these concepts or do you need further examples?

Survivor39, I noticed that you're currently doing a PhD in science (I'm presuming) at Cambridge. How awesome is that?

6. ## Re: Reliability, validity and accuracy: What's the difference.

i remember what validity is by associating it with the word believable. is the data believable? For reliability, I think repetition - have I repeated the experiment enough to ensure reliability?

7. ## Re: Reliability, validity and accuracy: What's the difference.

This is a useful analogy.

If you throw darts and they land in roughly the same area, your throw is said to be reliable.

If you throw the darts and they land in bull's eye, your throw is accurate.

However, reliable throws are not always accurate.

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