Student’s r-test

METH-induced changes in neuropeptide levels, selective Dj (SCH 23390) and D2 (sulpiride) dopaminergic receptor antagonists were coadministered. The results are expressed as percent of control to facilitate comparisons each value represents the mean SEM of five to seven animals. Data were subjeeted to either a Student s r-test (figures 4 and 5) or ANOVA analysis followed by a multiple comparisons test (figures 1, 2, and 3). Signifieanee was set at the. 05 level. 

Traditionally, the determination of a difference in costs between groups has been made using the Student s r-test or analysis of variance (ANOVA) (univariate analysis) and ordinary least-squares regression (multivariable analysis). The recent proposal of the generalized linear model promises to improve the predictive power of multivariable analyses. 

The most commonly employed univariate statistical methods are analysis of variance (ANOVA) and Student s r-test [8]. These methods are parametric, that is, they require that the populations studied be approximately normally distributed. Some non-parametric methods are also popular, as, f r example, Kruskal-Wallis ANOVA and Mann-Whitney s U-test [9]. A key feature of univariate statistical methods is that data are analysed one variable at a rime (OVAT). This means that any information contained in the relation between the variables is not included in the OVAT analysis. Univariate methods are the most commonly used methods, irrespective of the nature of the data. Thus, in a recent issue of the European Journal of Pharmacology (Vol. 137), 20 out of 23 research reports used multivariate measurement. However, all of them were analysed by univariate methods. 

The quantity of RNA extracted from FFPE cell/tissue sections by the heating and nonheating methods, and extracted from fresh cell/tissue embedded in OCT without fixation, was comparable, showing no significant difference for all yields of RNA by Student s r-test, with the exception of one sample, MDA cells fixed in formalin for 24h (p < 0.05). 

Six to nine separate immunocytochemical experiments were run for each primary antibody. Individual experiments were composed of at least two or three tissue sections of each animal from each group. Ten to 14 fields were analyzed for each brain region. Interexperimental differences were not statistically significant. Values represent the mean SD of experiments performed for each marker and treatment. The statistical study was performed by applying a two-tailed Student s r-test to the results of the quantitative analysis and by assuming... 

See Section 15.7 for abbreviations. Kinetic constants represent a minimum of three determinations standard deviation. No significant difference was found between r- and c-pepsin at the various pH values using a Student s r-test at the 0.05 level of significance. 

Because of the way r is defined, its value always lies between 0 and 1. Values close to 1 indicate a strong relationship, whereas values near zero imply little relationship. It is possible to use a version of the Student s t-test (Miller and Miller 1993) to see if the observed correlation is significant at a particular level of confidence (usually 95%), or to conclude that such a correlation may have occurred by chance. The equation for this is ... 

Fig. 12. Effect of spontaneous apoptosis on the activation of caspase-3 in human eosinophils. Eosinophils (2 x 10 /ml) were cultured for 3 h. Cells were lysed and caspase-3 activity was measured by caspase-3 colorimetric assay kit (R D Systems). Enzymatic products were measured at 405 nm with BIOTEK EL340 ELISA microplate reader (BIO-TEK Instrument Inc., Vermont). Human recombinant caspase-3 (5 U) (Calbiochem, California) was used as a positive control. The stimulation index was determined by direct comparison to the level of the normal control. Background readings from cell lysates and buffers were substracted from the readings of both induced and uninduced samples samples before calculating the stimulation index in caspase-3 activity. The differences between control and treated groups were assessed by Student s i-test. P < 0.05 P < 0.001 (Z2).

Figure 11. 3H-Thymidine uptake in PBL from S. typhimurium-r/j/ec/ec/ and uninfected calves stimulated with various antigens. Each bar shows the mean of log values of Sist with standard deviations indicated. Statistical analyses were made using Student s t test. (Reproduced with permission from Ref 59. Copyright 1982. Infect. ImmunJ...

The test to determine whether the bias is significant incorporates the Student s t-test. The method for calculating the t-test statistic is shown in equation 38-10 using MathCad symbolic notation. Equations 38-8 and 38-9 are used to calculate the standard deviation of the differences between the sums of X and Y for both analytical methods A and B, whereas equation 38-10 is used to calculate the standard deviation of the mean. The r-table statistic for comparison of the test statistic is given in equations 38-11 and 38-12. The F-statistic and t-statistic tables can be found in standard statistical texts such as references [1-3]. The null hypothesis Hf) states that there is no systematic difference between the two methods, whereas the alternate hypothesis Hf) states that there is a significant systematic difference between the methods. It can be seen from these results that the bias is significant between these two methods and that METHOD B has results biased by 0.084 above the results obtained by METHOD A. The estimated bias is given by the Mean Difference calculation. 

DM = Dry matter p = Significance level. Student s t-test r = Correlation coefficient. 

The Student s f-test was used in this evaluation to determine the level of treatment observation significance, compared with the baseline measurement. Because multiple 95% Mests were used in this evaluation, the r-test table values were adjusted for the multiple estimates by means of modified a values, a, as described by Dixon and Massey [9] a = 1 — (1 — a), where k is the number of confidence levels performed in the study. 

In practice, the population standard deviation, sample mean with the true mean must be based on Students t test. The test statistic is derived from Student s r-distribution as follows ... 

Table 35.1 Effects of thiamine on visceral fat mass in OLETF rats. Thiamine decreased visceral fat mass in Otsuka Long-Evans Tokushima Fatty (OLETF) rats. Retroperitoneal fat, epididymal fat and tibial length were determined at both 25 weeks (25 W) and 55 weeks (55 W) of age. Values are mean SE (n = 8). R<0.05, P<0.01 and / <0.001 by unpaired, two-tailed Student s t test. Modified from Tanaka, Kohda et al. (2010).

The tests were conducted for 1% aqueous solutions of SML/ESMIS mixtures. The T-02 tester was manufactured at the Institute for Sustainable Technologies-National Research Institute in Poland. The balls of /2-in. diameter were made of LH 15 bearing steel. Snrface ronghness was R, = 0.032 pm. The device was employed to measure motion resistance, wear, and antiseizure abilities in the presence of a lubricant. The methodology of the tests is described in the literature [130]. The values of the quantities measnred are arithmetic means of three independent measurements. The errors were evaluated with Student s 1-test at a confidence level of 0.90. 

Student s t test When adding a parameter to a model, the Student s t test, for significance, should be greater than 95% (p > 0.05). r When comparing models a significant increase in the correlation coefficient r should be realized to justify the addition of a new term or the abandonment of a model. An increase of 0.05-0.1 in r is an estimate of a significant increase. 

The confidence limits for the slope are given by fc where the r-value is taken at the desired confidence level and (A — 2) degrees of freedom. Similarly, the confidence limits for the intercept are given by a ts. The closeness of x to X is answered in terms of a confidence interval for that extends from an upper confidence (UCL) to a lower confidence (LCL) level. Let us choose 95% for the confidence interval. Then, remembering that this is a two-tailed test (UCL and LCL), we obtain from a table of Student s t distribution the critical value of L (U975) the appropriate number of degrees of freedom. 

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