# Understanding Statistical Power and Significance Testing — an Interactive Visualization

## Null and Alternative Hypothesis Real

Describes how to test the null hypothesis that some estimate is due to chance vs the alternative hypothesis that there is some statistically significant effect. From their Latin translations, an hypothesis is what you "suppose;" a thesis is what you "pose" (or "posit"). An hypothesis is what you do before you examine, analyze, critique, argue, and verify the evidence for or against your hypothesis. A thesis is what you conclude to after you do all this difficult work. Thus an hypothesis is what you suppose just 'off the face' of things. A thesis is what you pose after deeper examination.

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## Null hypothesis - Wikipedia

The null hypothesis and the alternate hypothesis are types of conjectures used in statistical tests, which are formal methods of reaching conclusions or making decisions on the basis of data. The hypotheses are conjectures about a statistical model of the population, which are based on a sample of the population. The tests. In order to undertake hypothesis testing you need to express your research hypothesis as a null and alternative hypothesis. The null hypothesis and alternative hypothesis are statements regarding the differences or effects that occur in the population. You will use your sample to test which statement (i.e., the null hypothesis or alternative hypothesis) is most likely (although technically, you test the evidence against the null hypothesis). So, with respect to our teaching example, the null and alternative hypothesis will reflect statements about all statistics students on graduate management courses. The null hypothesis is essentially the "devil's advocate" position. That is, it assumes that whatever you are trying to prove did not happen ( it usually states that something equals zero). For example, the two different teaching methods did not result in different exam performances (i.e., zero difference). Another example might be that there is no relationship between anxiety and athletic performance (i.e., the slope is zero).

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## State the null and alternative hypotheses LearnZillion

In this lesson you will learn how to change a research question into a statistical hypothesis by stating the null and alternative hypotheses. In statistical hypothesis testing, the alternative hypothesis (or maintained hypothesis or research hypothesis) and the null hypothesis are the two rival hypotheses which are compared by a statistical hypothesis test. In the domain of science two rival hypotheses can be compared by explanatory power and predictive power. An example is where water quality in a stream has been observed over many years, and a test is made of the null hypothesis that "there is no change in quality between the first and second halves of the data", against the alternative hypothesis that "the quality is poorer in the second half of the record". The concept of an alternative hypothesis in testing was devised by Jerzy Neyman and Egon Pearson, and it is used in the Neyman–Pearson lemma. It forms a major component in modern statistical hypothesis testing.

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## Setting the Hypotheses Examples STAT 100

State Null and Alternative Hypotheses. Null Hypothesis Students in the College of Arts and Architecture are no more likely to be left-handed than people in the general population population percent of left-handed students in the College of Art and Architecture = 10% or p =.10. Alternative Hypothesis Students in the. It is understood that bias may be intentional or unconscious, thus no dishonesty is implied by blinding. If both tester and subject are blinded, the trial is called a double-blind experiment. Blind testing is used wherever items are to be compared without influences from testers' preferences or expectations, for example in clinical trials to evaluate the effectiveness of medicinal drugs and procedures without placebo effect, observer bias, or conscious deception; and comparative testing of commercial products to objectively assess user preferences without being influenced by branding and other properties not being tested. Blinding can be imposed on researchers, technicians, or subjects. Blind experiments are an important tool of the scientific method, in many fields of research—medicine, psychology and the social sciences, natural sciences such as physics and biology, applied sciences such as market research, and many others. In some disciplines, such as medicinal drug testing, blind experiments are considered essential.

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## Null and Alternative Hypothesis | Real Statistics Using Excel

Aug 13, 2012. This Concept introduces students to developing the null and alternative hypotheses. Generally to understand some characteristic of the general population we take a random sample and study the corresponding property of the sample. We then determine whether any conclusions we reach about the sample are representative of the population. This is done by choosing an estimator function for the characteristic (of the population) we want to study and then applying this function to the sample to obtain an estimate. By using the appropriate statistical test we then determine whether this estimate is based solely on chance. The hypothesis that the estimate is based solely on chance is called the null hypothesis. Thus, the null hypothesis is true if the observed data (in the sample) do not differ from what would be expected on the basis of chance alone. The complement of the null hypothesis is called the alternative hypothesis. The null hypothesis is typically abbreviated as H is false), it is sufficient to define the null hypothesis.

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Learn what a hypothesis test is, 3 testing methods and how to interpret p values. Download Excel Add-in 30 day trial. The process begins by developing a research question. For example, does the new medication, Lovastatin, reduce cholesterol levels? The research question is converted into a formal scientific hypothesis, which has two parts: The . The null hypothesis is stated suggesting that the medication has no effect on cholesterol. In a setting of a clinical trial with treatment and placebo groups, the null hypothesis would be phrased, “Persons (i.e. a population of persons) treated with lovastatin have the same cholesterol levels as persons not treated with lovastatin. The alternate hypothesis would be stated, “Persons treated with lovastatin have different (higher or lower) cholesterol levels than persons not treated with lovastatin. This alternate hypothesis is stated as a 2-tailed hypothesis, which considers it possible that lovastatin has the opposite effect of that anticipated by the researchers.

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## How to Insert the Null Hypothesis & Alternate Hypothesis Symbols in Microsoft Word | Techwalla.com

Identifying the Null and Alternate Hypotheses The following flowchart can be helpful for identifying the null and alternate hypothesis of a claim. It is a statement about a parameter (a numerical characteristic of the population). These population values might be proportions or means or differences between means or proportions or correlations or odds ratios or any other numerical summary of the population. Hypotheses with One Sample of One Categorical Variable About 10% of the human population is left-handed. The is typically the research hypothesis of interest. Suppose a researcher at Penn State speculates that students in the College of Arts and Architecture are more likely to be left-handed than people found in the general population. We only have one sample since we will be comparing a population proportion based on a sample value to a known population value. Hypotheses with One Sample of One Measurement Variable A generic brand of the anti-histamine Diphenhydramine markets a capsule with a 50 milligram dose. The manufacturer is worried that the machine that fills the capsules has come out of calibration and is no longer creating capsules with the appropriate dosage. Hypotheses with Two Samples of One Categorical Variable Many people are starting to prefer vegetarian meals on a regular basis.

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## Null Hypothesis Definition and Examples, How to State - Statistics How To

Jan 9, 2017. Video created by University of London for the course "Statistics for International Business". For statistical analysis to work properly, it's essential to have a proper sample, drawn from a population of items of interest that have measured. According to the US Census Bureau, 64% of US citizens age 18 or older voted in the 2004 election. Suppose we believe that percentage is higher for ECC students for the 2008 presidential election. To determine if our suspicions are correct, we collect information from a random sample of 500 ECC students. Of those, 460 were citizens and 18 or older in time for the election. (We have some students still in high school, and some who do not yet have citizenship.) Of those who were eligible to vote, 326 (or about 71%) say that they did vote. Problem: Based on this random sample, do we have enough evidence to say that the percentage of ECC students who were eligible to vote and did vote in the 2008 presidential election was higher than the proportion of US citizens who voted in the 2004 election? Obviously, this is higher than the national average. The thing to consider, though, is that this is just a of ECC students - it isn't every student. It's possible that the students who just happened to be in our sample were those who voted. In order to determine if it really is that different from the national proportion, we need to find out how probable a sample proportion of 71% would be if the true proportion was really 64%.

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## Null and Alternative Hypotheses - YouTube

Aug 7, 2010. - where you can find free lectures, videos, and exercises, as well as get your questions answered on our forums! Hypothesis testing involves the careful construction of two statements: the null hypothesis and the alternative hypothesis. These hypotheses can look very similar, but are actually different. How do we know which hypothesis is the null and which one is the alternative? We will see that there are a few ways to tell the difference. The null hypothesis reflects that there will be no observed effect for our experiment. The null hypothesis is what we attempt to find evidence against in our hypothesis test.

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This lesson will give the definition of a null hypothesis, as well as an alternative hypothesis. Examples will be given to clearly illustrate the. Generation of the hypothesis is the beginning of a scientific process. It refers to a supposition, based on reasoning and evidence. The researcher examines it through observations and experiments, which then provides facts and forecast possible outcomes. The hypothesis can be inductive or deductive, simple or complex, null or alternative. While the null hypothesis is the hypothesis, which is to be actually tested, whereas alternative hypothesis gives an alternative to the null hypothesis.

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## Overview null hypothesis and alternative - Durham

Student Academic Learning Services Page 1 of 7 Student Services Building SSB, Room 204 905.721.2000 ext. 2491 Although the symbols for the null hypothesis and alternative hypothesis -- sometimes called the alternate hypothesis -- do not exist as special characters in Microsoft Word, they are easily created with subscripts. The alternate hypothesis is symbolically represented by a capitalized "H," followed by a subscript "1," although some researchers prefer an "a." The null hypothesis is represented by a capitalized "H," followed by a subscript "0" or "o." The accepted practice in the scientific community is to use two hypotheses when testing the relationship between two events. The alternative hypothesis states that the two events are related. However, scientists have found that testing for a direct correlation can cause bias in the testing procedure. To avoid this bias, scientists test a null hypothesis that states there is no correlation. By disproving the null hypothesis, you imply a correlation in the alternate hypothesis. A similar system is used in the United States legal system where a defendant is found "not guilty," rather than being found "innocent."Open your document in Microsoft Word and click wherever you want the hypothesis symbols to appear. Click the subscript button, located in the "Font" group of the "Home" tab. This button's icon looks like an "x" with a subscript "2." Alternatively, hold the "Ctrl" key and press "=".

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## Null Hypothesis Definition and

Null Hypothesis Overview. The null hypothesis, H 0 is the commonly accepted fact; it is the opposite of the alternate hypothesis. Researchers work to reject, nullify. It is a method for comparing 3 or more means by using multiple F Tests. For ANOVA we must develop a Null and Alternative Hypothesis, and once again the " = " goes with H. (All means are equal) Ha: at least one mean is different from the others. The Test Statistic F = the variance between samples / the variance within samples. (sample is also called treatment or factor) To look up the F critical value we need: the numerator degrees of freedom (k-1) the denominator degrees of freedom k(n-1) Where "k" is the number of different samples (also called treatments, or factors) "n" is the number of items within each sample. In a One Way ANOVA we are comparing only one variable from each sample. One Way ANOVA Hot peppers are officially measured in laboratory units called scovill units. On a common scale they are "taste tested" and ranked on a scale from 1 to 10 with 1 the mildest, 10 hottest. Four different peppers were considered for the "Salsa in a jar" from section #7. The taste test rankings from 12 of each type of pepper were as follows: Find: a) the variance between the different types of peppers, b) variance within each type of pepper, c) the F Test Statistic, d) the F critical value.

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## Hypothesis Testing -

Your hypothesis statement took the form of a prediction or speculation. Once the experiment has been carried out, you can now assess whether this prediction was correct or not. You should therefore have two hypotheses, the alternative and the null. H 1 The alternative hypothesis This is the research hypothesis. It is the. Identify the null hypothesis and alternative hypothesis from a given claim, and determine how to express both in symbolic form. What is needed is to do is explain what is going on in the Excel spreadsheet; basically, make a translation of the math into english. --- Null Hypothesis The housing price decline in Sacramento was equal to that of the nation between the years 20. H0 = National Means for Housing Price Decline - Alternative Hypothesis The housing price decline in Sacramento was greater to that of the nation between the years 20. H1 National Means for Housing Price Decline --- Project fulfills the one sample / one-tailed Z Test requirement This is the problem: Identify the null hypothesis and alternative hypothesis from a given claim, and determine how to express both in symbolic form. Hi, This is a situation that should be tested using a z test, since you have more than 30 scores in your sample and you know your population standard deviation. That means you'd have used the following formula: z=xbar-mu/(sigma/sqrt(n)), where xbar is your sample (City A) mean, mu is your population (national) mean, sigma is your population standard deviation, and n is your sample size. You didn't have your population standard deviation calculated in the Excel file, so I've calculated it and highlighted ...

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