 # ANOVA & t-tests

Hand Calculation of ANOVA. Repeated Measures ANOVA - Understanding a Repeated Measures ANOVA. Introduction Repeated measures ANOVA is the equivalent of the one-way ANOVA, but for related, not independent groups, and is the extension of the dependent t-test. Chap8. T-test online. Compare two means, two proportions or counts online. Simple Interactive Statistical Analysis Input. Compare two independent samples Counted numbers. To test for the significance of a difference between two Poisson counts. Input two observed counts in the top two boxes. Select options and hit the calculate button. General Linear Model. « PreviousHomeNext » The General Linear Model (GLM) underlies most of the statistical analyses that are used in applied and social research. It is the foundation for the t-test, Analysis of Variance (ANOVA), Analysis of Covariance (ANCOVA), regression analysis, and many of the multivariate methods including factor analysis, cluster analysis, multidimensional scaling, discriminant function analysis, canonical correlation, and others. Because of its generality, the model is important for students of social research. Although a deep understanding of the GLM requires some advanced statistics training, I will attempt here to introduce the concept and provide a non-statistical description.

The Two-Variable Linear Model. Questions and answers about language testing statistics: Effect size and eta squared. Shiken: JALT Testing & Evaluation SIG Newsletter Vol. 12 No. 2. Apr. 2008. (p. 38 - 43) [ISSN 1881-5537] PDF Version. Eta squared hcr. Onewayrmspss. RepeatedMeasuresANOVA. Learn Math and Stats with Dr. G. ANOVA Testing Example Excel Example for this ANOVA See a HOW TO Video of this Example A research study compared the ounces of coffee consumed daily between three groups. Group1 was Italians, Group 2 French, and Group 3 American. Determine if there is a significant difference among the groups using a 5% level (alpha is .05). Group1: Italian Group 2: French Group 3: American The Results of this study are in the following table: Note that here in this example: “n” is the sample size for each group.

Two-way anova - Handbook of Biological Statistics. This is a draft of the Third Edition of this handbook. It may change at any time. Until this is finished, you may want to use the Second Edition. Summary Use two-way anova when you have one measurement variable and two nominal variables, and each value of one nominal variable is found in combination with each value of the other nominal variable. Degrees of Freedom Tutorial. A lot of researchers seem to be struggling with their understanding of the statistical concept of degrees of freedom. Most do not really care about why degrees of freedom are important to statistical tests, but just want to know how to calculate and report them. This page will help. For those interested in learning more about degrees of freedom, take a look at the following resources: I couldn’t find any resource on the web that explains calculating degrees of freedom in a simple and clear manner and believe this page will fill that void. It reflects my current understanding of degrees of freedom, based on what I read in textbooks and scattered sources on the web. ANOVA. Determine sample size two-way ANOVA? Computing required sample size for experiments to be analyzed by ANOVA is pretty complicated, with lots of possiblilities. To learn more, consult books by Cohen or Bausell and Li, but plan to spend at least several hours. Two-way ANOVA, as you'd expect, is more complicated than one-way. The complexity comes from the many possible ways to phrase your question about sample size. The rest of this article strips away most of these choices, and helps you determine sample size in one common situation, where you can make the following assumptions: There are two levels of the first factor, say the factor is Drug and you either gave the drug or gave vehicle (placebo).

If those limitations aren't a problem for you, then read on for a simple way to compute necessary sample size. Sample size is always determined to detect some hypothetical difference. What about units? Complex ANOVA 2 factor flashcards. Analysis of Variance (ANOVA) - StatsDirect. Problem of alpha inflation. The main problem that designers of post hoc tests try to deal with is -inflation. This refers to the fact that the more tests you conduct at = .05, the more likely you are to claim you have a significant result when you shouldn't have (i.e., a Type I error). Doing all possible pairwise comparisons on the above five means (i.e., 10 comparisons) would increase the overall chance of a Type I error to i.e., a 40.1% chance of making a Type I error somewhere among your six t-tests (instead of 5%)!! The overall chance of a Type I error rate in a particular experiment is referred to as the experimentwise error rate (sometimes called Familywise error rate). ANOVA - Main. Microsoft Word - sstypes.doc - sstypes.pdf. Between-Groups, Within Groups. Research Methods and Statistics: A Critical Thinking Approach - Sherri L. Jackson. Introduction to ANOVA. Introduction to ANOVA (Jump to: Lecture | Video ) Assumptions of Statistical Tests. “All models are incorrect. Some are useful.” George Box When you do a statistical test, you are, in essence, testing if the assumptions are valid. We are typically only interested in one, the null hypothesis. That is, the assumption that the difference is zero (actually it could test if the difference were any amount). Multiple Hypothesis Testing.

## Degrees of Freedom

T-Tests. One Way ANOVA. Post Hoc. Two Way & Rpt Measures ANOVA. How To Identify Patterns in Time Series Data: Time Series Analysis. In the following topics, we will first review techniques used to identify patterns in time series data (such as smoothing and curve fitting techniques and autocorrelations), then we will introduce a general class of models that can be used to represent time series data and generate predictions (autoregressive and moving average models). Finally, we will review some simple but commonly used modeling and forecasting techniques based on linear regression.

For more information see the topics below. General Introduction In the following topics, we will review techniques that are useful for analyzing time series data, that is, sequences of measurements that follow non-random orders. Unlike the analyses of random samples of observations that are discussed in the context of most other statistics, the analysis of time series is based on the assumption that successive values in the data file represent consecutive measurements taken at equally spaced time intervals.