Suppose we want to test the claim that the population mean is larger than 35 or the mean score of 38. Hypothesis testing the intent of hypothesis testing is formally examine two opposing conjectures hypotheses, h 0 and h a these two hypotheses are mutually exclusive and exhaustive so that one is true to the exclusion of the other we accumulate evidence collect and analyze sample information for the purpose of determining which of. Independent data 4 spss does this really well but you do need the raw data1. In this course you will learn how to carry out a selection of these using the statistical analysis software package spss. This quick start guide shows you how to carry out a onesample ttest using. In the example above we had two variables, car age and car colour, the data types were. Therefore, we can reject the null hypothesis at the 0. During this talk, i will try to briefly address pros and cons of both approaches and. The first part covers the mean ttest, and kolmogorove smirrnov test. Millery mathematics department brown university providence, ri 02912 abstract we present the various methods of hypothesis testing that one typically encounters in a mathematical statistics course. The statistics tutors quick guide to commonly used statistical tests. We are able to test, say, the hypothesis that some variable has no e. Hypothesis testing is a systematic procedure for deciding whether the results of a research study support a particular theory which applies to a population.
In chapter 1, the authors intend to build on the title of the book by elaborating on the concepts and steps of statistical hypothesis testing, with. Descriptive and inferential statistics 4 the department of statistics and data sciences, the university of texas at austin click on the arrow button that will move those variables to the variables box. Plan for these notes i describing a random variable i expected value and variance i probability density function i normal distribution i reading the table of the standard normal i hypothesis testing on the mean i the basic intuition i level of signi cance, pvalue and power of a test i an example michele pi er lsehypothesis testing for beginnersaugust, 2011 3 53. If you are working with summary statistics use one of the online calculators found here. Notice that this is a onesided test because were testing if one mean is less than another, instead of if the two means are not equal to each other. The number of scores that are free to vary when estimating a population parameter from a sample df n 1 for a singlesample t test. The focus will be on conditions for using each test, the hypothesis. Hypothesis testing hypothesis testing allows us to use a sample to decide between two statements made about a population characteristic. Alternative hypothesis h1 mean earnings for 1997 are less than the mean earnings for 1996. The variable of interest, older, is on a ratio scale, so a zscore test or a ttest might be appropriate.
Students often go straight to the hypothesis test rather than investigating the data with. In a trial a jury must decide between two hypotheses. The second tool is the probability density function i a probability density function pdf is a function that covers an area representing the probability of realizations of the underlying values i understanding a pdf is all we need to understand hypothesis testing i pdfs are more intuitive with continuous random variables. Hypothesis testing non statistical hypothesis testing a criminal trial is an example of hypothesis testing without the statistics. Analysing data using spss sheffield hallam university. The student will learn the big picture of what a hypothesis test is in statistics.
Hypothesis testing using spss training nyim training nyc. Hypothesis testing is the formal statistical technique of collecting data to answer questions through the use of a statistical model. Hypothesis testing is explained here in simple steps and with very easy to understand examples. I am working a data analysis manual using r and a text on foursteps to hypothesis testing will be. These types of question can be answered by carrying out hypothesis tests. Aug 20, 2014 the student will learn the big picture of what a hypothesis test is in statistics. Hypothesis testing the center for applied statistics and. It will usually give you a test statistic z and the pvalue. Step 4 make the decision to reject or not reject the null hypothesis. Generally you only have to input the proportion or number of successes and the sample size for each sample and hit a calculate button somewhere. Spss does this really well but you do need the raw data. Ill post instructions as soon as i get that version.
We are now going to look at formal hypothesis testing. For example, a population might be all the individuals that live in the united. Hypothesis testing is the fundamental and the most important concept of statistics used in six sigma and data analysis. Each question asked needs to be posed as a null hypothesis. It also provides techniques for the analysis of multivariate data, speci. In this example, the significance p value of levenes test is. Bayesian statistical methods are becoming increasingly popular and often seen in direct opposition with the frequentist null hypothesis significance testing nhst. Population characteristics are things like the mean of a population or the proportion of the population who have a particular property. The onesample t test procedure tests whether the mean of a single variable differs from a specified constant. Exercise using spss to explore hypothesis testing one.
Hypothesis testing uses sample data to evaluate a hypothesis about a population. For example, the variables salbegin and salary have been selected in this manner in the above example. Determine if this is a onetailed or a twotailed test. It lists the heights for 10 men and 12 women collected at truman state university. In this section, we describe the four steps of hypothesis testing that were briefly introduced in section 8. Continued while the null hypothesis is maintained to be true throughout a hypothesis test, until sample data lead to a rejection, the aim of a hypothesis test is often to disprove the null hypothesis in favor of the alternative hypothesis.
The language accepted by pspp is similar to those accepted by spss statistical products. Explore the many graphical and statistical options in the spss menu that you can use to conduct the appropriate hypothesis test correctly learn how to interpret the spss output and make decisions in regards to the hypothesis test. Hypothesis testing with t tests university of michigan. The dialogue allows selection of any scale variable from the box at the left and a test value that represents a hypothetical mean. However, we need some exact statement as a starting point for statistical significance testing. Not known ttest 2 spss does this really well but you do need the raw data. Hypothesis testing type i and type ii errors statistical.
Hypothesis testing p value statistical hypothesis testing. We will discuss terms such as the null hypothesis, the alternate hypothesis, statistical significance of a. Practice running inferential statistics such as correlations, independent and pairedsamples t test in order to test hypotheses and output statistical. Before using this information and the product it supports, read the information in the notices section. In this method, we test some hypothesis by determining the likelihood that a sample statistic could have been selected, if the hypothesis regarding the population parameter were true. Define the population under study state the hypothesis that is under investigation give the significance level select a sample from the population collect the data. A step by step guide to data analysis using ibm spss 5th ed. Field a 2009 discovering statistics using spss, 3rd edn. Throughout this manual, we will employ the rebranded name, spss. This edition applies to ibm spss amos 24 and to all subsequent releases and modifications until otherwise indicated in new editions. A practical guide for those unfortunate enough to have to actually do it. A negative correlation indicates that high scores on one variable are associated with low scores on the other variable. This lets us know that men make more per hour than women.
The data have been weighted according to the instructions from the national. The details of pspps language are given later in this manual. Testing a hypothesis that two variables are uncorrelated. This writeup substantiates the role of a hypothesis, steps in hypothesis testing and its application in the course of a research. Interpreting hypothesis testing results the marble example also can be used to interpret informative hypothesis testing results from a single study. First, select cases sex1 so that only the males are selected. This provides methods for data description, simple inference for continuous and categorical data and linear regression and is, therefore, suf. Descriptive and inferential statistics 5 the department of statistics and data sciences, the university of texas at austin for anticipating further analyses. The example to the right is data on reaction times after drinking. To perform a one sample ttest click analyzecompare meansone sample ttest and the following dialog box will appear. Write 350 words describing the results of the test and explain how the use of this hypothesis testing can be used to evaluate solutions to your research issue. For a twosided directional test, the correct directional decision will be made in at least 100 s t% of all possible samples thus we can be at least.
Microsoft product screenshots reproduced with permission from microsoft corporation. The defendant is innocent the alternative hypothesis or research hypothesis is h1. Step 2 find the critical values from the appropriate table. We dont usually believe our null hypothesis or h 0 to be true. Define the population under study state the hypothesis that is under investigation give the significance. Spss doesnt tell you directly which one is larger, but since you know there is a difference, look at the group statistics and see that the mean for men is 12. Framework of hypothesis testing two ways to operate.
Click here for online calculators that work well with summary statistics. A hypothesis testing is the pillar of true research findings. A null hypothesis is a precise statement about a population that we try to reject with sample data. The goal of this exercise is to explore hypothesis testing and the onesample t test. Oct 14, 2010 field a 2009 discovering statistics using spss, 3rd edn. Hi, i am an industrial engineer, hypothesis testing is done for the purpose of testing a sample for some attribute fo population and is done through p and ttests, i will do tests in minitab or excel, kindly contact m more. To do so, every statistical analysis includes a hypothesis test. Singlesinglesample sample ttests yhypothesis test in which we compare data from one sample to a population for which we know the mean but not the standard deviation. Intro to hypothesis testing in statistics hypothesis. Onesample ttest in spss statistics procedure, output and. This fact has been useful for hypothesis testing, both of sample means and of regression coe.
In chapter 7, we will be looking at the situation when a simple random sample is taken from a large population with. Because the hypothesis involves the phrase greater than, this must be a one tailed test. Hypothesis testing or significance testing is a method for testing a claim or hypothesis about a parameter in a population, using data measured in a sample. Null hypothesis h0 mean earnings for 1997 are greater than or equal to the mean earnings for 1996. Hypothesis testing santorico page 290 hypothesis test procedure traditional method step 1 state the hypotheses and identify the claim. Known spss doesnt do this the same way it is done in the book. Specifically, we demonstrate procedures for running dependentsample or onesample ttests, independentsample ttests, differencesample or matched or pairedsample ttests. Also explained is the pvalue and how to interpret it.
A clear and fairly consise guide to performing the most commom tests in spss including. General statistics and hypothesis testing spss tutorial. These two statements are called the null hypothesis and the. In chapter 1, the authors intend to build on the title of the book by elaborating on the concepts and steps of statistical hypothesis testing, with a brief historical background. In virtually every field of work, the need to be confident and competent in analysing data and drawing conclusions is extremely useful. Hypothesis testing below is a sample data set that we will be using for todays exercise. We have tried here to avoid manual calculation and make sure that you. Pdf bayesian hypothesis testing with spss amos sara. The data will be entered in the same way that it was in the spss introduction handout.
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