Reliability and Validity, NEED HELP (1 Viewer)

mkv_86

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I have a science research project due tomorrow, and it says that I have to explain how i achieved reliability and validity in my experiment. I understand both of the terms, but I dont know what to exactly write. Can someone give me a list of things I should write about achieving my reliability and validity?

Much thanks;)
 

Shuuya

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Reliabilty: say you repeated the experiement multiple times to exclude outliers, then averaged results

Validity: say that you made sure to control all variables apart from the ones you were testing

That's really general stuff haha. What was your experiment?
 

leehuan

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If you know that reliability is anticipating consistency, then you should expect to perform the same experiment over and over as Shuuya pointed out. If there is consistency then you have achieved your target. Outliers should always be ignored in the results. (Note that you can be reliable but inaccurate - you can get the wrong results over and over again)
For the HSC course, you can almost always use the averaging method to determine your results. A better approach, however, is to use a line of best fit.

If you know that validity is expecting the method to achieve the aim, then your experiment should be conducted in a relevant manner. The primary way to do this again, what Shuuya said.

This is because usually you test for one thing at a time, not all at once
 

mkv_86

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Reliabilty: say you repeated the experiement multiple times to exclude outliers, then averaged results

Validity: say that you made sure to control all variables apart from the ones you were testing

That's really general stuff haha. What was your experiment?
My experiment is based on a question which is - "does the pH level of a soil, determine a plant's growth?"
 

mkv_86

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So this is what I have wrote down for reliability.
My experiment is basically, I am growing plants on different types of soils (local soil which is backyard soil, potty mix, clay and gravel), im using sunflowers because they grow really fast, ive made 3 trials, ive completed them and made the results and stuff already. Im also testing each soils ph level, Ive used 2 methods which is written below, one of them is basic consisting of inserting a pH meter into the soil and recording the reading of the pH meter and the second method is slightly more complicated.

Reliability is a term which, can be achieved by repeating certain methods and create trials to construct a reliable experiment. I have utilised two alternate methods to investigate the pH level of the different soils. The first, simple method was to utilise a pH meter and then record the pH reading, for each soil. However, this isn't particularly accurate, as there is a possibly of debris and microorganisms living in the soil, which could potentially interfere with the pH meter's reading, and as a result utilising a second, more precise, and complicated method, will definately increase the reliability of the experiment. The second method consists of extracting, the soil substance, with a combination of distilled water, into a container, so that any debris, originally from the soil, will remain and the rest of the soil substance will be combined with the distilled water, creating pure soil liquid substance. The next process was to insert the pH meter, for pure pH reading, without any disruptions from soil debris. When the pH meter was positioned into the soil, as well as the extraction, the process of putting the pH meter in and out, three times, was a reliable action, as sometimes the pH reading could possibly be incorrect. Creating extra methods, to deliver more precise and optimal results, as well as repeating those methods, more than once, is a way which reliability was achieved in this investigation. During the process of growing plants, reliability was achieved by consistently growing the plants for 3 weeks and then repeating the process, for a total of 3 times. Consistency was achieved through continually recording the plant's height, and maintaining the plants, by hydrating them daily, as well as taking pictures, and creating results.

All these processes have contributed, so that the experiment achieved reliability.


What do you think? I need some feedback thanks
 

the_matrix

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From looking at the question, I can point of a few points that ensure validity:

- make sure the plants tested have same size/height/of the same species
- make sure sunlight, humidity levels are the same for all trials
- if watering plants, make sure same amounts of water are sprayed on every plant
- ensure amount of soil in every pot is the same
 

mkv_86

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From looking at the question, I can point of a few points that ensure validity:

- make sure the plants tested have same size/height/of the same species
- make sure sunlight, humidity levels are the same for all trials
- if watering plants, make sure same amounts of water are sprayed on every plant
- ensure amount of soil in every pot is the same
thank you, finally I can write something.
 

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