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Thread: evaluating findings

  1. #1 evaluating findings 
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    Hey

    In an experiment, eg how different concentrations of acid affect the rate of mg dissolving.

    Does anyone know how to:

    Identify any control variables that cannot be controlled

    Evaluate findings in terms of bias, reliability and validity,

    assess level of bias.


    Last edited by Seaturtle; December 10th, 2011 at 03:27 AM.
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  3. #2  
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    The answers for those questions vary widely by discipline and sub-discipline and I think could be why you aren't getting much response.

    Perhaps provide an example of a hypothesis and test being considered...


    Meteorologist/Naturalist & Retired Soldier
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  4. #3  
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    Like if you do an experiment with Mg and different concentrations of acid and you have to evaluate your findings and write a conclusion in terms of bias,reliability and validity.
    But how do you assess the level of bias in this experiment?
    And identify any cotroll variables that cannot be controlled?
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  5. #4  
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    Seaturtle, what exactly is it that you are investigating in your experiment?

    My guess is, you're trying to evaluate the dependence of reaction rate on the concentration of reactants. If so, ask yourself what else affects reaction rate other than the variable you are investigating (which is the concentration of acid). For example, temperature, pressure..etc., all affect reaction rate. So, think about whether or not you are making sure that these remain constant throughout the experiment.
    What parameter is it that you are using to measure the rate? Let's say you are measuring the volume of gas evolving as a product of this reaction. Think about the method you are using to make this measurement, and whether this this method is reliable.
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  6. #5  
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    thank you
    Last edited by Seaturtle; December 9th, 2011 at 02:42 PM.
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  7. #6  
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    Thank you for the reply
    I am investigating how the concentration of acid effects the time taken for Mg to dissolve. Surface area, pressure, temperature and catalysts can all affect the reaction rate. I will keep these constant by using mg powder roughly the same size and the same mass to keep the surface area the same, the temperature is going to be just the room temperature and we aren't going to use a catalyst. So these variables can be controlled in the experiment. I am measuring how much time it takes for mg to dissolve in different concentrations of acid.

    But that is just one example i am going to do another experiment. In this one I am going to find out how changing the temperture affect aerobic respiration in yeast cells. so we are going to mix oxygen and glucose to form carbon dioxide, water and energy. oxygen+glucose -> water + carbon dioxide + energy
    Independant variable - Temperature
    Dependant Variable - Volume of Carbon Dioxide produced

    So far i have wrote a prediction : i predict that as the temperature increases the volume of carbon dioxide produced also increases, then i explained how the collision theary, the lock and key theory (enzymes) and respiration affects the rate of the reaction.

    But when i write a conclusion for this experiment, i don't really know how to assess the level of bias and validity
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