## Paired Samples T-Test

The Student’s paired samples t-test (sometimes called a dependent-samples t-test) is used to test the null hypothesis that the difference between pairs of measurements is equal to zero. A low p-value suggests that the null hypothesis is not true, and that the difference between the measurement pairs is not zero.

The Student’s paired samples t-test assumes that pair differences follow a normal distribution – in the case that one is unwilling to assume this, the non-parametric Wilcoxon signed-rank can be used in it’s place (However, note that the Wilcoxon signed-rank has a slightly different null hypothesis; that the two groups of measurements follow the same distribution).

### Arguments

 data the data as a data frame pairs a list of lists specifying the pairs of measurement in data students TRUE (default) or FALSE, perform Student's t-tests bf TRUE or FALSE (default), provide Bayes factors bfPrior a number between 0.5 and 2 (default 0.707), the prior width to use in calculating Bayes factors wilcoxon TRUE or FALSE (default), perform Wilcoxon signed rank tests hypothesis 'different' (default), 'oneGreater' or 'twoGreater', the alternative hypothesis; measure 1 different to measure 2, measure 1 greater than measure 2, and measure 2 greater than measure 1 respectively norm TRUE or FALSE (default), perform Shapiro-wilk normality tests qq TRUE or FALSE (default), provide a Q-Q plot of residuals meanDiff TRUE or FALSE (default), provide means and standard errors effectSize TRUE or FALSE (default), provide effect sizes ci TRUE or FALSE (default), provide confidence intervals ciWidth a number between 50 and 99.9 (default: 95), the width of confidence intervals desc TRUE or FALSE (default), provide descriptive statistics plots TRUE or FALSE (default), provide descriptive plots miss 'perAnalysis' or 'listwise', how to handle missing values; 'perAnalysis' excludes missing values for individual dependent variables, 'listwise' excludes a row from all analyses if one of its entries is missing

### Returns

A results object containing:

 results\$ttest a table results\$norm a table results\$desc a table results\$plots an array of groups

Tables can be converted to data frames with asDF or as.data.frame(). For example:

results\$ttest\$asDF

as.data.frame(results\$ttest)

Elements in arrays can be accessed with [[n]]. For example:

results\$plots[] # accesses the first element