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# Experimental Design Notes

Extracts from this document...

Introduction

Designing Your Own Experiment * Hypothesis: an explanation of an observation, written as a statement and testable. Can be based on previous knowledge * Variables o a characteristic or property capable of taking on a range of values and with the potential to affect things o Independent variables: variable set before starting the investigation o Dependent variables: variable that is measured during the investigation o Control variables: factor kept the same in the investigation * Parts of Experimental Method o Aim- purpose of the experiment o Hypothesis o Prediction o Method: physical steps required to test hypothesis and predictions * Things to consider * Materials needed * Variable * Sample size and replication of experiment * Experimental Design o Preliminary o Aim and hypothesis o Hypothesis and predictions are testable with resources available o Assumptions and variables * Awareness of assumptions that you are making in experiment * All variables are identified * Independent variable range has been set * Layout of experiment considered * Data Collection o Units for all variables have been identified o Amount of data to be collected has been identified o Consideration of how data will be analyzed o Method for systematically recording results * Repeat or Trials: investigation that is carried out again at a different time * Ensures experiment is reproducible and data is consistent * Treatments: well defined conditions applied to the sample o Specific and predetermined * Sample o subset of a whole used to estimate the values that might have been obtained if every individual was measured * Data o What is it going to look like? ...read more.

Middle

o Controlled experiments o Advantages o All factors other than the one hypo to be causing the effect can be kept constant o Comparative method Stats 2 * Reliability of the Mean o Variance is other measure of dispersion o 1 method calculate standard error * Standard Error o Allows for calculation of the 95 percent confidence interval o CI used to indicate relativity of an estimate o Degrees of freedom = n-1 o Calculated 955 of it can be plotted as error bars on a graph o Smaller CI more reliable the data staminate o Determines if there's a significant difference between sets of data * T-test o Only valid for certain situations o 2 group tests o Only have 2 samples to compare o Assumptions o Normal and not skewed distribution o SD for both samples is similar * Null hypothesis- the hypothesis of no difference or no effect * Probability that chance alone could make a difference have an effect * 5% = difference is due to chance 5% of the time * Degree of freedom = sum of total number of sample sizes of both groups * Steps o Calculate degree of freedom o V1 + V2 -1 = DF o Look at t values and match degree of freedom now with t value column o Values lie between 1 and 5 percent o Reject null hypothesis when P is 5 or less Microscopy o History o 1st century Ad glass as invented, Roman observed it and tested o Experimented with different designs o Thick in ...read more.

Conclusion

begin developing * Germination o Beginning of growth o Growth in a seed calls it a seedling o Process where the seed begins to grow * Seed Germination Dependency o Internal and external o Water o Temperature o Oxygen o Light * Start of Germination o Begins with water- called imbibitions o Seed takes up water, undergoes metabolic changes o Activates bio chemical process resulting in protein synthesis o Oxygen = seed metabolism and energy production o Seeds that are waterlogged or buried too deeply in soil won't get enough oxygen needed * Steps of Germination o Seed gets water, seed coat bursts o Chemical energy provides the energy needed for the embryo to enlarge and push out of the seed coat o Tip of root comes out first and anchors plant and lets plan absorb minerals and water form soil * Plant Vocab o Cotyledon: embryonic leaf inside the seed o Monocotyledon: one of two major groups of plants has only 1 cotyledon ex onions corn lilies o Diacotyledon: other major group of plants, 2 cotyledons, beans, castor oil plant * Monocot Germination o Primary root pierces seed coat and grows downward o Primary leaf grows up and is protected by the coleptile, hallow cylindrical structure o When the seedling is above round the coleptile stops growing * Dicot Germination o As embryo grows seeds out shoot called a radical o Radical becomes primary root and grows o Hypocotyls then emerges and lifts grouping tip o With light, hypocotyls straightens and cotyledons spread apart to expose the primary leaves ...read more.

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