Note: If you use this approach on an exam, you may also want to mention why this approach is appropriate. For this example: Paired t test For differences between PEFR Before and PEFR After: Mean of differences = 56.111111 (n = 9) Standard deviation = 34.173983 Standard error = All Rights Reserved. View Mobile Version Skip to Content Eberly College of Science STAT 200 Elementary Statistics Home » Lesson 9: Comparing Two Groups 9.5 - Comparing Paired Means Printer-friendly versionPaired Data Paired data

The population data are symmetric, unimodal, without outliers, and the sample size is 15 or less. P-value. Use the matched-pairs t-test to determine whether the difference between sample means for paired data is significantly different from the hypothesized difference between population means. Interpret results.

Texas Instruments TI-84 Plus Silver Edition Graphing Calculator, SilverList Price: $189.00Buy Used: $53.88Buy New: $229.99Approved for AP Statistics and CalculusIntermediate Statistics For DummiesDeborah J. Your cache administrator is webmaster. Casey FlemingList Price: $24.88Buy Used: $17.26Buy New: $24.88Barron's AP StatisticsMartin Sternstein Ph.D.List Price: $16.99Buy Used: $0.01Buy New: $5.00Casio(R) FX-9750GPlus Graphing CalculatorList Price: $99.99Buy Used: $9.95Buy New: $81.99Approved for AP Statistics and Search Course Materials Faculty login (PSU Access Account) Lessons Lesson 0: Statistics: The “Big Picture” Lesson 1: Gathering Data Lesson 2: Turning Data Into Information Lesson 3: Probability - 1 Variable

The other two sets of hypotheses (Sets 2 and 3) are one-tailed tests, since an extreme value on only one side of the sampling distribution would cause a researcher to reject When testing hypotheses about a mean difference, a t distribution is used to find the p value. We use the t Distribution Calculator to find P(t < -1.307) = 0.103, and P(t > 1.307) = 0.103. Calculation The value of t may be calculated using packages such as SPSS.

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| Menu | Quick | Books | Share | Search | Settings | Matched-pair However, that doesn't necessarily mean a real difference isn't present in the population of all students. Thus, the P-value = 0.103 + 0.103 = 0.206. To find the statistic, follow these steps: Calculate the differences for each pair (they're shown in column 4 of the above table).That is, if one is true, the other must be false; and vice versa. For more detailed analysis of this type, see agreement analysis. Melde dich an, um dieses Video zur Playlist "Später ansehen" hinzuzufügen. Specifically, the approach is appropriate because the sampling method was simple random sampling, the samples consisted of paired data, and the mean differences were normally distributed.

The P-value is the probability of observing a sample statistic as extreme as the test statistic. Analyze sample data. For example, think of studying the effectiveness of a diet plan. Generated Fri, 14 Oct 2016 11:05:04 GMT by s_ac5 (squid/3.5.20)

Don't confuse t tests with correlation and regression. Easy! Use an 0.05 level of significance. sd = sqrt [ (Σ(di - d)2 / (n - 1) ] where di is the difference for pair i, d is the sample mean of the differences, and n is

Is the mean difference less than 0? Schließen Ja, ich möchte sie behalten Rückgängig machen Schließen Dieses Video ist nicht verfügbar. pleasantness of two different types of chocolate). Compute the standard deviation (sd) of the differences computed from n matched pairs.

The t tests (and related nonparametric tests) compare exactly two groups. The null hypothesis will be rejected if the difference between sample means is too big or if it is too small. The hypothesis test then boils down to a test for one population mean. Then, all of the students were given an IQ test.

Example The results of two sets of measures are as follows: X1 X2 X1-X2 (X1-X2)^2 5.24 7.53 -2.29 5.24 6.13 7.81 -1.68 2.82 6.15 8.79 -2.64 To run this example, open the test workbook using the open file function of the file menu then choose paired t test from the parametric methods section of the analysis menu. AP Statistics Tutorial Exploring Data ▸ The basics ▾ Variables ▾ Population vs sample ▾ Central tendency ▾ Variability ▾ Position ▸ Charts and graphs ▾ Patterns in data ▾ Dotplots Wird geladen...

Anmelden 42 0 Dieses Video gefällt dir nicht? Calculate the mean, and the standard deviation, sd, of all the differences. Reading Scores for Computer Game Method versus Phonics Method Student Pair Computer Method Phonics Method Difference (CM – PM) 1 85 80 +5 2 80 80 0 3 95 88 +7 Formulate an Analysis Plan The analysis plan describes how to use sample data to accept or reject the null hypothesis.

Caution: Changing format will erase your data. 3. Test Your Understanding Problem Forty-four sixth graders were randomly selected from a school district. d = x1 - x2 where x1 is the value of variable x in the first data set, and x2 is the value of the variable from the second data set Power is calculated as the power achieved with the given sample size and variance for detecting the observed mean difference with a two-sided type I error probability of (100-CI%)% (Dupont, 1990).

The test statistic is a t statistic (t) defined by the following equation. The hypotheses are stated in such a way that they are mutually exclusive. Hypothesis Testing: Two Sample Groups: Paired t - test (part 2) - Dauer: 8:50 Red River College Wise Guys 11.634 Aufrufe 8:50 t-Test with Paired (Dependent) Samples - Dauer: 14:17 TuitionKit Analyze Sample Data Using sample data, find the standard deviation, standard error, degrees of freedom, test statistic, and the P-value associated with the test statistic.

The test is conducted on paired data. (As a result, the data sets are not independent.) The sampling distribution is approximately normal, which is generally true if any of the following The t test compares one variable (perhaps blood pressure) between two groups. Diese Funktion ist zurzeit nicht verfügbar. Choose calculator 3.

The p-value in this case is greater than 0.10 (and hence greater than 0.05) because 1.36 is smaller than (or to the left of) the value of 1.38 on the table, Thus, the P-value = 0.103 + 0.103 = 0.206. The system returned: (22) Invalid argument The remote host or network may be down. Enter mean, SD and N.

The test statistic is calculated as: - where d bar is the mean difference, s² is the sample variance, n is the sample size and t is a Student t quantile The t-value can also be interpreted as an r-value, which can be calculated as: r = SQRT( t2 / (t2 + DF)) where DF is the degrees of freedom. Standard deviation. Hinzufügen Möchtest du dieses Video später noch einmal ansehen?

Select category 2. By examining the differences in the pairs of observations, you really only have a single data set, and you only have a hypothesis test for one population mean.