In hypothesis testing, we use sample data to choose between two competing hypotheses. There are versions of spss for windows 98, 2000, me, nt, xp, major unix platforms solaris, linux, aix, and macintosh. The null hypothesis is the starting point for statistical significance testing. In these cases, the underlying parameters of two different populations are compared.
Spss hypothesis testing all the help you need spss help. It lists the heights for 10 men and 12 women collected at truman state university. The data will be entered in the same way that it was in the spss introduction handout. Hypothesis testing santorico page 290 hypothesis test procedure traditional method step 1 state the hypotheses and identify the claim. Hypothesis testing is drastically overused tests are often performed when they are irrelevant. Spss originally, statistical package for the social sciences was released in its first version in 1968. It is used by market researchers, health researchers, survey companies, government, education researchers, marketing organizations and others. Spss uses a students t distribution to conduct the test regardless of the sample size or the knowledge of population standard deviation the p value produced by spss is the one for the twotailed test, that is, h0. In this book, we describe the most popular, spss for windows, although most features are shared by the other versions.
To carry out a two sample ttest in spss data must be stacked i. For example, a null hypothesis may also state that the correlation between frustration and aggression. Hypothesis testing introduction the whole idea here is that were going to determine whether we can reject some assumption about a population given information about some sample. Lecture 5 hypothesis testing in multiple linear regression. Using spss to understand research and data analysis. This includes the spss output, and how to interpret the output. Computing the test statistic conceptually, the chisquare test of independence statistic is computed by summing the difference between the expected and observed frequencies for each cell in the table divided by the expected frequencies for the cell. Hypothesis testing one type of statistical inference, estimation, was discussed in chapter 5. For example, you could choose to test your hypothesis by conducting a simple correlational study. Do not reject h 0 because of insu cient evidence to support h 1.
This is a partial test because j depends on all of the other predictors x i, i 6 j that are in the model. In the example above we had two variables, car age and car colour, the data types were different, the. Basic concepts and methodology for the health sciences 3. A good reference on using spss is spss for windows version 23. Onesample ttest in spss statistics procedure, output and. This exercise uses compare means means and independentsamples t test to explore hypothesis testing. However, please note that this is a onetail righttail test, and so the p.
To carry out a two sample t test in spss data must be stacked i. 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. General statistics and hypothesis testing spss tutorial. If you are not familiar with spss or need more information about how to get spss to read your data, you may wish to read our spss for windows. H0 must contain condition of equality,or 6 estt the null hypothesis directly. The independent samples t test can be used to see if two means are different from each other when the two samples that the means are based on were taken. When it comes to hypothesis testing for a two sample. The method of hypothesis testing can be summarized in four steps.
Spss can not be used with only the summarizing statistics mean, standard deviation, sample size. Hypothesis testing the center for applied statistics and. 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 lse hypothesis testing for beginnersaugust, 2011 3 53. The hypothesis testing paradigm and onesample tests a. Hypothesis testing ibm spss essentials wiley online library. Preface spss, standing for statistical package for the social sciences, is a powerful, userfriendly software package for the manipulation and statistical analysis of data. Is the unemployment rate related to the crime rate. This exercise uses compare means and oneway analysis of variance to explore hypothesis testing. To open existing spss data files we use the commands file open dat. The t testing the null hypothesis that the intercept is zero is of no interest, but those testing the partial slopes are.
In this case, it doesnt really matter, because the twotailed pvalue is 0. Rejection by an irrelevant test is sometimes viewed as license to forget statistics in further analysis a wildlife example. For example, if you open an excel file it may ask which worksheet and. My goal is to give you enough information to use spss to perform some different hypothesis tests without getting into the nitty gritty detail. Hypothesis testing ibm spss essentials wiley online.
Take a closer look at the 2012 bike share survey apply anova and correlations to items from that survey apply regression analysis do that after watching the corresponding lecture learn how to systematically develop and test hypotheses apply that to a. To complete this assignment, you will use the following data. Variable calculated from sample data and used in hypothesis test. The output below was produced using spss version 15. The two sample t test is equivalent to the 1, 1 contrast on the two means when the design includes only two groups. Spss does this really well but you do need the raw data. The goal of this exercise is to explore hypothesis testing and the onesample t test. Page 1 of 30 north south university, school of business mkt 631 marketing research instructor. O the statistical hypothesis testing consists of following steps components 1.
As with any other test of significance, after the test statistic has been. The other type, hypothesis testing,is discussed in this chapter. Independent samples ttest means that there are two groups, and we are. Ibm spss statistics 23 is wellsuited for survey research, though by no means is.
Step 4 make the decision to reject or not reject the null hypothesis. In hypothesis testing, there are 2 choices, the null hypothesis and the alternative hypothesis. Conscientiousness does make a significant, unique, contribution towards predicting ar, t48 4. This exercise uses compare means onesample t test and select cases in spss to explore hypothesis testing and the onesample t test. The analyses reported in this book are based on spss version 11. Hypothesis testing hypothesis testing framework a trial as a hypothesis test hypothesis testing is very much like a court trial. In a trial, the burden of proof is on the prosecution. Students often go straight to the hypothesis test rather than investigating the data with summary. The pvalue is the twotailed pvalue for the hypothesis test tha. 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.
We identify the value and probability for this test statistic from the spss statistical. Two sample inference in our first look at hypothesis testing, we focused on one sample tests. The test statistic is based on variable 1 variable 2. Framework of hypothesis testing two ways to operate. Basic concepts and methodology for the health sciences 5. Being a student of osteopathy, he is unfamiliar with basic expressions like \random variables or \ probability density functions. H0 must contain condition of equality,or 6 estt the null hypothesis. Make a mental note of the variety of available statistical calculators. With the hypothesis stated, you can now test it by conducting a study in which you gather and analyze some relevant data. Data can be defined as a collection of scores obtained when a subjects characteristics andor performance are assessed. All the data files used in this presentation can be found at the link below. You assume innocence until shown guilty beyond a reasonable doubt.
How to run and interpret the results for the one sample t test in spss is shown in this video part 1 of 2. Lecture 12 hypothesis testing allatorvostudomanyi egyetem. The form of the t test is slightly different for the independent samples and dependent samples types of two sample tests, and spss has separate procedures for performing the two types of tests. The null hypothesis, symbolized by h0, is a statistical hypothesis that states that there is no difference between a parameter and a specific value or that there is no difference between two parameters. Take a closer look at the 2012 bike share survey apply anova and correlations to items from that survey apply regression analysis do that after watching the corresponding lecture learn how to systematically develop and test hypotheses apply. It is used to test the null hypothesis that two samples come from the same population i. For this example we are testing the following hypotheses in the two sample tt. Conduct and interpret hypothesis tests for two population means.
These notes o er a very simpli ed explanation of the topic. The example to the right is data on reaction times after drinking. Two population means and two population proportions1 10. We will present sample programs for some basic statistical tests in spss, including t tests, chi square. Do the examples yourself by completing each step in spss. Start spss by clicking the start button then selecting all programs ibm spss statistics ibm spss statistics 23. The test statistic t is a standardized difference between the means of the two samples. Summary one of the most important distinctions students make as a statistician is between descriptive and inferential statistics. The statistics tutors quick guide to commonly used statistical tests. In spss, the user concludes the test by comparing the p value of the test statistic to the level of significance the method of using p values to. Testing hypotheses chapter 9 12 how to do open the file gss93 subset. This week, we look at two sample hypothesis testing problems.
The violation of this assumption is more serious than violat. The package is particularly useful for students and researchers. The hypothesis we want to test is if h 1 is \likely true. Reject h 0 and accept 1 because of su cient evidence in the sample in favor or h 1. Understand the relation between hypothesis testing, confidence intervals, likelihood and bayesian methods and their uses for inference purposes. Can you make up some hypothesis about the population in 1.
Thus, this is a test of the contribution of x j given the other predictors in the model. Intro to hypothesis testing in statistics hypothesis. In this example, 20 petri dishes, each with 10 celery seeds, were observed for. The method of hypothesis testing can be summarized in four.
For this example we are testing the following hypotheses in the two sample t test. What is a pvalue how to use a pvalue to make the statistical decision in step 6 of whether to reject or fail to reject the null hypothesis. There are two hypotheses involved in hypothesis testing null hypothesis h 0. 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. Hypothesis testing is very much like a court trial. A handbook of statistical analyses using spss academia.
Transfer one variable to variable 1 and the other to variable 2. In a hypothesis test, the burden of proof is on the unusual claim. Analysing data using spss sheffield hallam university. Take notes on the explanations of the resulting spss output files.
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. It is a statement of what we believe is true if our sample data cause us to reject the null hypothesis text book. Graphs and analyses will not be saved unless you save them specially. For example, a population might be all the individuals that live in the united states at a particular. Steps components in testing of statistical hypothesis. Exercise using spss to explore hypothesis testing one. Example spss output for ttest for difference in means.
My goal is to give you enough information to use spss to perform some different hypothesis tests. An overview of statistical tests in spss spss learning modules. In spss, doing a onesample t test will automatically give you a confidence interval as well defaults to 95%. Defendant is guilty collect data the null hypothesis is the ordinary state of affairs.
You a sample of 100 light bulbs and determine their mean lifetime. It must be in the form of rowscases and columnsvariables. Chapter 6 hypothesis testing university of pittsburgh. It is much harder to know what a pvalue actually means in plain english. Mahmood hussain, phd data analysis for marketing research using spss introduction in this part of the class, we will learn various data analysis techniques that can be used in marketing research. Details of the statistical hypothesis are discussed in the steps or components in testing of statistical hypothesis. Nevertheless, the profession expects him to know the basics of hypothesis testing. We compared a sample mean to a population parameter that was known. Have spss open on your computer as you read the chapter. Pairedsamples t test this opens another dialogue box. The first set of hypotheses is testing the variance while the proceeding.
Hypothesis testing below is a sample data set that we will be using for todays exercise. In the second section, the chisquare test of independence, independent and paired sample t tests, bivariate correlations, regression, and the general linear model will be covered. Ttest in spss hypothesis tests of proportions confidence. To select the variable to perform a frequency table for example the exposure. Hypothesis testing about spss spss is a computer program used for statistical analysis. The ttest for the difference in means is an hypothesis test that tests the null. First, we set out the example we use to explain the onesample ttest procedure in spss statistics. Note that even though we used a grouping variable that only had two values male, female. This is because there are two primary purposes for statistics. We are now going to look at formal hypothesis testing. Conduct and interpret hypothesis tests for two population means, population standard deviations known. A hypothesis test uses the data from a sample to decide between a null hypothesis and an alternative hypothesis concerning the value of a parameters in the population.
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