...Elements of a Test of Hypothesis 1. Null Hypothesis (H0 ) - A statement about the values of population parameters which we accept until proven false. 2. Alternative or Research Hypothesis (Ha )- A statement that contradicts the null hypothesis. It represents researcher’s claim about the population parameters. This will be accepted only when data provides sufficient evidence to establish its truth. 3. Test Statistic - A sample statistic (often a formula) that is used to decide whether to reject H0 . 4. Rejection Region- It consists of all values of the test statistic for which H0 is rejected. This rejection region is selected in such a way that the probability of rejecting true H0 is equal to α (a small number usually 0.05). The value of α is referred to as the level of significance of the test. 5. Assumptions - Statements about the population(s) being sampled. 6. Calculation of the test statistic and conclusion- Reject H0 if the calculated value of the test statistic falls in the rejection region. Otherwise, do not reject H0 . 7. P-value or significance probability is defined as proportion of samples that would be unfavourable to H0 (assuming H0 is true) if the observed sample is considered unfavourable to H0 . If the p-value is smaller than α, then reject H0 . Remark: 1. If you fix α = 0.05 for your test, then you are allowed to reject true null hypothesis 5% of the time in repeated application of your test rule. 2. If the p-value of a test is 0.20 (say) and you reject H0 then, under...
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...Math 1150 April 18, 2012 Hypothesis Test Barry Bonds Analysis For the analysis of Mr. Bonds, we need to define the years of alleged drug use and pick a suitable statistic. Mr. Bonds has been accused of using performance-enhancing drugs at the end of 1998. Mr. Bonds only participated in 14 games in 2005 due to various factors. This disruption in the normal process provides a good place to break after the alleged drug use. The key performance metric for batters tends to be their Batting Average (BA). Mr. Bonds’ batting average from 1986 to 1998 is .289, and his average from 1999 to 2004 is .329. Since a larger batting average is better, Mr. Bonds’ average BA did improve in the alleged drug-use years. However, is the difference in his Batting Average due to random variation, or is it large enough to say that he actually improved? The hypothesis test for Mr. Bonds would be: H0: Mr. Bonds’ average BA was the same before and after H1: Mr. Bonds’ average BA was different after alleged drug use The chances of getting it wrong (probability of a Type I Error) using the available statistics and it came out to 3%. Put another way, if we conclude that Mr. Bonds’ average BA is different during the period of alleged drug use, then we would be wrong only 3 times in 100. As I said before, we typically would like the chance of getting it wrong to be less than 5% to conclude the averages are different. In this case, the chance of getting it wrong is less than 5%, so I would conclude that...
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...solve our problem scientifically: Observation This is the first part of scientific method is discovered upon direct observation of what is around us. As a scientist we have to look critically and attempt to avoid all kind if sources and bias in this observation. Ask question The second step in the scientific method is formulated by questions. Ask as many questions as we need to answer. Science can answer many questions, but there are some which cannot be answered by science. Hypothesis The next part of our scientific method is to form a hypothesis. This is simply an educated guess as to the answer for the question. Prediction The prediction is an official way to put a hypothesis to a test. If the test works most likely we are on a right track to solve our problem. If we have carefully designed our hypothesis to be sure it is falsifiable, then we know precisely what to predict. The prediction has three parts such as if, then and when. Experiment This is where we practice hands-on part of the test. Here we will carry out our manipulation and compare the results with results from a control setting. To be an experiment, we must compare all the results of many manipulations. Not everything we do in science...
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...The Scientific Method: Observation and Hypothesis INTRODUCTION By now, you have examined a variety of phenomena in the natural world A focus of environmental science is to explain these phenomena. That is, what are the causes and effects of such phenomena? How does one go about investigating the causes and effects such that the conclusions are meaningful and reliable? The answer is the scientific method, which uses designed experiments and careful observations to investigate causes and effects. The scientific method is the systematic procedure for investigation, which generally is composed of the following: 1. Observe a phenomenon 2. Formulate a hypothesis: a tentative description that explains your observation 3. Design and conduct an experiment to test the hypothesis 4. Present your results 5. Interpret the results that validate or modify the hypothesis Step 1—Observed Phenomenon Suppose you observe that an environmental phenomenon (e.g., rainbow trout, Salmo gairdneri are no longer present in a nearby polluted river). You could conduct research by examining the literature to determine what other studies have been done to help you find an explanation. However, the studies may not be directly applicable. You might want to design and conduct your own study. Step 2—Formulate a Hypothesis The second step is to formulate a hypothesis. A hypothesis is a statement of the cause and effect in a specific situation. It is a...
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...Scientific Method Steps of the Scientific Method 1. Observation/State a question or problem 2. Form a Hypothesis 3. Experiment 4. Collect Data 5. Analysis 6. Conclusion 7. Revise Hypothesis or Repeat Experiment Observations/State the question or problem • Notice (Observe) some problem or question to investigate • Observation is not the same as an inference – Using observations to draw a conclusion about a situation without any proof Form a Hypothesis • Must be testable, supportable, falsifyable • “Educated Guess” is not enough. You must be able to test your explanation and have reasons to support your hypothesis – EX: I believe that students are more talkative after lunch because of the caffeine they drink. Experiment • Design an experiment that tests your hypothesis using: – Control: compare results to a standard (control) • Ex: 1 group gets a placebo, the other gets the drug to be tested – Variables: • Independent variable is changed by the scientist. It is usually listed on the X (horizontal) axis. • Dependent variable changes as a result of the changes in the independent variable. It is usually graphed on the Y (vertical) axis. • Example: Changes in the temperature over time. What are the variables, and which is which? Data/Analysis • 2 types of data can be collected through experimentation – Quantitative: using measurements/numbers as the primary source of data) • EX: mass, length, volume – Qualitative (also known as descriptive):using...
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...Scientific inquiry in biology starts by observing the living species around you. What separates science from the other methods of seeking truth is that it is testable (e.g., one can devise experiments to test the validity of an idea); it is falsifiable (e.g., an experiment can reveal if an idea is false); and it involves natural causality (e.g., the method involves and depends upon the natural laws of the universe which cause things to happen in a predictable and repeatable manner). Observation: Scientific inquiry begins when something interesting gets your attention. Question: Following an observation, a question arises in your mind. It may be something like "I wonder what?" or, "I wonder how? or, "I wonder why?" Assignment Details In this assignment, you will take a look at the scientific method. You will design a (fictional) scientific study to answer a specific question based upon an observation. First, choose 1 of the following observations or questions: •Option A ◦Observation: During the winter, you spread salt daily on your driveway to melt the snow. In the springtime, when the lawn begins to grow, you notice that there is no grass growing for about 3 inches from the driveway. Furthermore, the grass seems to be growing more slowly up to about 1 foot from the driveway. ◦Question: Might grass growth be inhibited by salt? •Option B ◦Observation: You and your neighbor have small kitchen gardens where you both grow tomatoes. His blotchy green and...
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...RESEARCH HYPOTHESES AND QUESTIONS A research hypothesis is a prediction of the outcome of a study. The prediction may be based on an educated guess or a formal theory. Example 1 is a hypothesis for a nonexperimental study. Example 1 It is hypothesized that first grade girls will show better reading comprehension than first grade boys. In Example 1, the author is predicting that he or she will find higher comprehension among girls than boys. To test it, a nonexperimental study would be appropriate because nothing in the hy-pothesis suggests that treatments will be given. A simple research hypothesis predicts a rela-tionship between two variables. From your study of variables, it should be clear that the two variables in Example 1 are (1) gender and (2) reading comprehension. The hy-pothesis states that reading comprehension is re-lated to gender. Example 2 is a hypothesis for an experimen-tal study. Example 2 It is hypothesized that children who arc shown a video with mild violence will be more aggressive on the playground than those who are shown a similar video without the violence. In Example 2, the independent variable is vio-lence (mild vs. none), and the dependent variable is aggressiveness on the playground. The hypotheses in Examples 1 and 2 are ex-amples of directional hypotheses. In a direc-tional hypothesis, we predict which group will be higher or have more of something. Sometimes we have a nondirectional hy-pothesis. Consider Example 3...
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...evaluating and understanding the methods used in the core studies. Research Methods and Techniques used in Psychological Investigations ------------------------------------------------- Methods and Techniques ------------------------------------------------- ------------------------------------------------- Experimental Methods: ------------------------------------------------- ------------------------------------------------- The term experimental method refers to the method used to carry out the experiment. There are three main types of experiment – lab, field and natural/quasi. Research Method | Definition: | Advantage(s) | Disadvantage(s) | Laboratory experiment | A test under controlledconditions that is madeto demonstrate a knowntruth, examine the validityof a hypothesis, or determine the efficiency of something previously untried. | The research can better establish causality through reducing the number of confounds via a controlled environment like a lab setting. | The results may be artificial and not apply to the real world, there may be researcher bias or a social desirability affects, and the results may only apply to one situation and may be difficult to replicate or generalize. | Field experiment | 1. A field experiment applies the scientific method to experimentally examine an intervention in the real world (or as many experimentalists like to say, naturally occurring environments) rather than in the laboratory. | Less prone to demand characteristics...
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...to learn more about what makes plants grow. In this stage of the experiment I decide to use as many sources as I can find. The more information I have on the scientific experiment, the better the design of my experiment is going to be. Hypothesis is the next stage of the Scientific Method is known as the "hypothesis." This word basically means "a possible solution to a problem, based on knowledge and research." The hypothesis is a simple statement that defines what you think the outcome of your experiment will be. All of the first stage of the Scientific Method -- the observation, or research stage -- is designed to help you express a problem in a single question ("Does the amount of sunlight in a garden affect tomato size?") and propose an answer to the question based on what you know. The experiment that you will design is done to test the hypothesis. Topic: Does the amount of sunlight a tomato plant receive affect the size of the tomato? Hypothesis: I believe the more sunlight the tomato gets the bigger it will grow. My hypothesis is based on the tomato plants sunshine to make food through photosynthesis, and logically, more sun means more food and exploratory observation of plants in my garden. Prediction is the hypothesis is your general statement of how you...
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...solve problems and test hypotheses. 1. The first step to scientific method is to state the problem. It is important to clearly state what your problem is to avoid any confusion later in the scientific method. 2. The second step to scientific method is making observations about the problem. The scientific method consists of a series of steps used by scientists to conduct experiments. The word observation has two meanings in scientific method, first there the scientists observation of the world as it leads to the hypothetical theory (a theory that lacks merit) This is the first step of scientific method and can be presented in two ways either as a natural observation or a staged one, Second in the collection of data in a experiment using the scientific method there are two observations ,Qualitive and Quantive. The third step to scientific method is the hypothesis (a proposed explanation for a phenomenon) for a hypothesis to be scientific hypothesis; the scientific method requires that one can test it. 4. The fourth step to scientific method is the experiment to test an hypothesis. The experiment must be unbiased in nature meaning that scientists cannot create an experiment that will favor the outcome that they predicted in their hypothesis 5. The fifth and final step in scientific method is to draw a conclusion. Scientists draw conclusions by examining the data from an experiment and there are two outcomes. Either the experiment supported the hypothesis and can be regarded...
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...the results of your test samples if one or more of the test samples tested positive but the positive control did not work according to plan? 4) What tubes represent the positive control and negative controls in Procedures 3.1, 3.2, 3.3 and 3.4? 5) Procedure 3.1 step 11 Optional treatment (see exercise in this pdf) asked you to include a tube containing a known reducing sugar and Benedict’s reagent while omitting heat. What was...
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...Scenario 1: Ask a question: The scientific method is a cycle of observation, developing a hypothesis, experimentation based on the hypothesis, and identifying conclusions. Through successive rounds of the scientific method hypothesis are refined into theorems that can explain our observations. You reach for the switch and the light doesn't come on. What would you do next? Would you try the switch again? Did I flick it all the way first time? Then I would check to see if there was anything wrong with the electricity, by trying to turn on other lights in the house or looking to see if any electrical appliances were working. And so on and so forth until I found out why the light wasn't working. Do background research: The light doesn't come on the first time that I flick the switch. Based on experience I know a few potential causes of this observation, namely: faulty switch, no electricity, or burnt out light bulb. Using this background information I can then form a hypothesis as to why the light bulb didn't come on when I flicked the switch. Hypothesis: The light bulb didn't come on when I turned the switch because the light bulb has burnt out. Experiment: Take the old bulb and test it in a known working socket (at a neighbor's). Experiments should ideally have only two possible outcomes. Either they will support the hypothesis or disprove it. If the light doesn't work at my neighbor’s house then there is something wrong with the bulb. If it does then something else...
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...Hypothesis Identification Article Analysis RES/342 March 19, 2012 Hypothesis Identification Article Analysis Hypothesis is an educated guess about a specific subject in connection to nature. Researchers proceed by making experimentations of nature according to their observations. There is nothing that can researchers do with a data if hypothesis does not generate predictions. Often it is required that a scientific hypothesis must be testable. That means it must generate predictions. The phase “predictions” can be confusing, since we interpret it as telling about something that will happen, like "with in two years, 99% of the college student will be engage in academic dishonesty. In other words, a test (observations or experiments) must take place. Therefore, saying that a hypothesis generates predictions is similar to saying hypothesis is testable. In reference to the article “ACADEMIC DISHONESTY: PERCEPTION OF BUSINESS STUDENTS”, cheating among business students appears to be a major concern for professors and the colleges and Universities. This observation will prove that students with business major are more likely to engage in cheating on their examinations compared with students in other major fields. The author surveyed 5,000 students on 99 college campuses and reported that at least half of those in his sample practiced academic dishonesty (Bowers, 1964). Another survey was done in a 1993 by the same author across the same campuses and the result was higher...
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...the scientific method this include: observation, questioning, hypothesis, testing, and explanation. All of these steps together will allow a person to get to and answer on what it is they are researching. The scientific method can be used not only in science, but in everyday life. One can use this while making a new food or building a new car. It can also be used in the workplace as way to figure out how well that a new product will do out in the market. When using the scientific method the hypothesis that one comes up with must be accepted or rejected in the end after all steps have been completed. This will allow the person performing the tests to know if they need to do more research and experimenting, or if they have the right answer to the questions they are answering. The hypothesis in this method have the potential to make a long standing theory that many people can use and believe in for mnay years to come. (Barrow, 1991)(Kuhn, 1952) The experiment that was conducted on the scientific methods website proved that my prediction that the flower grew towards the window due to the fact the flower needed the light for energy true. I first observed that in the readings above my experiment that the flower grew towards the window, and I knew that it was because the flower needed the light. I then came up with the hypothesis that the flower grew towards the window due to the light. I then tested my hypothesis by planting three flowers, and placing two light one on the left...
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...working. As I explore though the house I find that the lights inside and outside the house are not working throughout. I have identified this by attempting to turn the lights on in each room with no luck of light. I know that if only one area of the house was affected that the issue would be likely found at the interior breaker of the home, but this is not the case. In developing a theory, I know none of the lights are working, which is an indicator that the problem is not a bulb issue or an interior breaker issue. I also know that the power company has no reported outages in the area. I do know that the house was built in the 50’s and the electrical panel has not been upgraded since the home was built. Based on this information my hypothesis is that issue is within the main breaker outside the home. Due to the age of the home and electrical panel, it is likely a burnt out fuse that has caused all the lights to not work. Just to be sure I have tested the interior breakers of the house by flipping them to the off position and back on, still no lights. I also tested the exterior breaker by flipping it to the off position and back on, still no light. Now by replacing the fuse and switching on the lights I have solved the problem and have light throughout the house. From the research above I have found the problem was in fact a burnt out fuse at the main breaker of the exterior of the house. Question 2: It’s dinner time, I have all the ingredients ready to cook but...
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