![]() Therefore, we calculate the difference between the scores, then we basicly consider them our sample to perform a one sample t-test. ![]() So the mean of the comparison distribution is always 0, as long as the null hypothesis posits no difference. According to the null hypothesis, there is no difference that is, the mean difference score is 0. With the paired-samples t test, we have a sample of difference scores. \ Step 3: Determine the characteristics of the comparison distribution Null hypothesis: Jobs in Boise pay the same, on average, as jobs in Los Angeles: \Īlternative hypothesis: Jobs in Boise pay different incomes, on average, from jobs in Los Angeles Remember, hypotheses are always about populations, not about our specific samples. Step 2: State the null and alternative hypotheses. The data were not randomly selected, so we should be cautious when generalizing beyond this sample of job types. We do not know whether the population is normally distributed, there are only 12 observations in total, and there is not much variability in the data in our samples, so we should proceed with caution. The hypothesis test will be a paired-samples t test because we have two samples, and all participants are in both samples. The comparison distribution will be a distribution of mean differences. Population 2: Job types in Los Angeles, California The comparison distribution is a distribution of mean difference scores (rather than a distribution of means). Step 1: Assumptionsįor the one-sample t test, we use individual scores for the paired-samples t test, we use difference scores. ![]() Notice that the same individual (income for specific job) is measured twice (two different cities). How can we conduct a paired-samples t test to determine whether income in one of these cities differs, on average, from income in the other? We will use a two-tailed test and a significant level of 0.05. # 6 Social worker (with bachelor's degree) 36963 43542 We looked up the 25th percentile for income for six jobs in two cities: Boise, Idaho, and Los Angeles, California. Salary Wizard is an online tool that allows you to look up incomes for specific jobs for cities in the United State. The main difference is that we are comparing the sample mean difference between scores to that for the mean difference for the population according to the null hypothesis, rather than comparing the sample mean of individual scores to the population mean. The steps are very similar to those for the ones we have seen before. The major difference in the paired-samples t test is that we must create difference scores for every individual. Once you understand the single-sample t test, the paired-samples t test is simple. The paired-samples t test (also called dependent-samples t test) is used to compare two means for situations in which every participant is in both samples (or situation of two set of units that are matched in pairs, for example, husbands and wives). Nolan and Thomas Heinzen (with a few modifications) Source: Statistics for the Behavioral Sciences - Susan A. Step by Step Solutions: T-tests: Paired/Dependent and Independent
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |