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# BIOSTATISTICS

INTRODUCTION ABOUT STEPS OF SCIENTIFIC METHODS AND USE OF STATISTICS IN SCIENCE

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## BIOSTATISTICS

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1. Scientific Methods

2. What's the scientific method? • The scientific method is one way that people can try to find the answer to problems that are bothering them.

3. How do I use the scientific method? • The scientific method is just a list of steps that you need to follow when you're solving a problem. • The Scientific Method is an organized way of figuring something out. There are usually six parts to it.

4. Is there only one Scientific Method? • conducting and analyzing an experiNo! There are several versions of this scientific process ranging in the number of steps. • However, all versions begin with a question to be answered based on observations of the world around us and provide an organized method for ment.

5. Steps for scientific method • Purpose • Research • Hypothesis • Materials • Experiment • Results • Conclusion and communicate to results

6. Step 1: Formulate a question • What do you want to know or explain? • Use observations you have made to write a question that addresses the problem or topic you want to investigate.

7. 1- Purpose • You've got a problem that you want to have solved. • The purpose step in the scientific method is just a restatement of what you want accomplished. • What do you want to find out? • What is your goal? • You should write just one sentence for your purpose. You'll see what I mean in the upcoming example.

8. Step 2: Research the question • This is an important step, especially when you do an independent investigation such as a science fair project. • Researching your question lets you know if others have done this same experiment before and if so, what their data suggests. If they had a widely accepted conclusion, you may want to try a different angle with your experiment or test a different variable. • You should also research the scientific concepts associated with the experiment. For example, if you are testing to see which paper towel brand is the most absorbent, you should research absorbency, paper material, and quality control testing. This will help answer the “WHY?”

9. 2- Research • Find out as much as you can. Look for information in books, on the internet, to get the most information you can before you start experimenting.

10. Step 3: Form a hypothesis • What do you think will happen? • A hypothesis is your prediction for the outcome of the experiment. • It is based on your observations and should be testable!

11. 3-Hypothesis • After doing your research, try to predict the answer to the problem. Another term for hypothesis is 'educated guess'. • This is usually stated like • " If I...(do something) then...(this will occur)"

12. 4-Materials • What do you need to have in order to see if your hypothesis is true? • This part of the scientific method is a list of everything you need to do the experiment.

13. Step 5: Conduct an experiment to test your hypothesis • Design a procedure that tests your hypothesis to see if your prediction is correct. • Record all of your data and observations and put them into a table that is neat and organized.

14. 5-Experiment Design a test or procedure to find out if your hypothesis is correct.

15. Example • An example, when grass seeds set up to grow under a green light bulb and seeds under a red lightand observe each for a couple of weeks. You would also set up grass seeds under regular white light so that you can compare it with the others. If you are doing this for a science fair, you will probably have to write down exactly what you did for your experiment step by step.

16. Step 6: Analyze data • Is your data reliable? Does it make sense? • Put your data into a chart or graph and look for any trends.

17. 6-Results When you did the experiment, • what happened? • What did you see, hear, smell, measure, ect? • You should give a complete accounting of all data that you take (sometimes this is referred to as the "Data" section). • There's an old saying among chemists: "If you didn't write it down, then it didn't happen." Make sure you write everything down!

18. Step 7: Draw conclusions • Do your data and observations support your hypothesis? • If you cannot make a definite conclusion, you may need to try the experiment again. • This means you may either need to rewrite your procedure if it was not specific enough; you may need to change your hypothesis.

19. 7- Conclusion • Review the data and check to see if your hypothesis was correct. • If the grass under the green light bulb grew faster, then you proved your hypothesis, • if not, your hypothesis was wrong. It is not "bad" if your hypothesis was wrong, because you still discovered something

20. Think you can name all seven steps?

21. A few other terms you may need to know

22. Variables • An experiment generally has three types: independent, dependent and controlled. When choosing your variables, keep in mind that good variables are usually those that you can measure with a number (e.g., concentrations of pollutants, time of day, temperature) or observe objectively (e.g., colors). • Subjective qualities, like whether noise pollution makes local birds happy or sad, are not appropriate variable

23. 1- Independent Variable This is the part of your experiment that you will test (vary) to answer your hypothesis. In the example above, the independent variable would be the different colors of the light bulbs.

24. The independent variable • The independent variable is the one that you, as the scientist, change or manipulate. Your experiment should have only one independent variable. ‘ • For Environ Mentors project, possible independent variables could be time (e.g., testing the amount of pesticides in the water at the same site on different days) or location (e.g., measuring noise pollution at different locations at the same time of day). • Time and location are just two examples of independent variables.

25. 2- Dependent Variable This is what occurs in response to the changing independent variable. In our example the Dependent Variable is how much the grass seeds grow.

26. Dependent variable • The dependent variable changes in a consistent manner in response to changes you make in the independent variable. • In the examples above which used time and location as the independent variables, the dependent variables would be the amount of pesticides in the water, and the amount of noise pollution, respectively. • Whereas there should only be one independent variable, the number of dependent variables can vary. For instance, if you were investigating water quality at the same site on different days, your independent variable would be time, and each different pesticide concentration you measure in the water would be a different dependent variable.

27. 3- Control The control should be the part of the experiment where you do not include the Independent Variable. In our example, grass seed that is growing under the white (uncolored) bulb would be your control. The control lets you compare your results in the experiment

28. Controlled variables (Constants) • The controlled variables are those that you try to keep constant throughout your experiment. • These are all variables that might affect your dependent variable. If you were measuring the concentrations of pesticides in water on different days, you would want to make sure that things like the weather and outside temperature remain relatively constant. You should keep track of your controlled variables as carefully as your other variables.

29. Remember that • it is important to try to keep your controlled variables as constant as possible. • For instance, if you measured the noise pollution at two different traffic intersections in your city (independent variable = location; • dependent variable = noise pollution) • but made your measurements at different times of day, you wouldn’t be able to tell if changes in the amount of noise pollution were due to the different location or the different time of day. Most experiments will have more than one controlled variable.

30. Sample Size Sample Size (N) • The number of subjects involved in experimentation • Increasing N • Decreases impact of chance events and error • Increase reliability of results

31. Validity The extent to which experimental results can be generalized to other settings or situations To increase validity, increase N

32. EXAMPLE 2

33. Lets put Science into Action • Observation • Research • Hypothesis • Controlled Experiment • Results • Conclusion

34. Controlled Experiment • The heart of science • Eliminates other causes so we can link a single cause with a single event.

35. Controlled Experiment • Hypothesis: If the water is polluted, then the fish will die. • Cause: Pollution • Effect: Death • Set up 2 groups to test the hypothesis • Control Group: Normal Conditions • No pollution in the water • Experimental Group: Change one thing • Put pollution in the water

36. Controlled Experiment • Independent Variable – What have I changed? • Presence or absense of pollution • Dependent Variable – What will I measure? • Number of dead fish

37. Controlled Experiment Synonyms

38. Data – Chart form

39. Data – Graph form Y axis – Dependent Variable – Number of live fish X axis – Independent Variable – Quantity of Pollution

40. Use the Data to draw a Conclusion • Hypothesis: If the water is polluted, then the fish will die. • Does the data agree (confirm) or disagree (refute) our hypothesis? • It is ok to disprove a hypothesis. What else might be going on?

41. Are there any new questions that could be asked? Creative Thinking is Key! Be Curious About the World

42. Science builds on prior knowledge • There is always more to learn!

43. A Little Practice with the Scientific Method

44. Bart believes that mice exposed to microwaves will become extra strong (maybe he’s been reading too much Radioactive Man). He decides to perform this experiment by placing 10 mice in a microwave for 10 seconds (do not do this at home, Bart is a misguided fictional character ). He compared these 10 mice to another 10 mice that had not been exposed. His test consisted of a heavy block of wood that blocked the mouse food. He found that 8 out of the 10 microwaved mice were able to push the block away. 7 out of 10 non-microwaved mice were able to do the same.

45. What was Bart’s hypothesis? Identify the Control group. Identify the independent and dependent variables What might be some of the possible constants? What should Bart’s conclusion be?

46. ANSWERS • Mice exposed to microwaves will be extra strong • The unexposed mice • Independent variable- microwaves Dependent variable- strength • Same block of wood, same food, time of day, approx same size mice, etc. • Microwave exposure does not significantly change the strength of mice.

47. Observe your world and come up with a question to answer using the Scientific Method!

48. H.W • ASK yourself a question       How…? What…? When…? Who…? Which…? Why…? Or Where…?               It must be something you can observe and measure. • Do Background Research on your topic Find out the techniques, materials and equipment to best investigate your subject.              Use the library and the internet. • Construct a Hypothesis    This is an educated guess or prediction about the answer to your question.    “If __(action)   , then   (this)   will happen.”

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