Calculates the exact power of two one sided t-tests (TOST) for one, two, and paired samples.

```
power_t_TOST(
n = NULL,
delta = 0,
sd = 1,
eqb,
low_eqbound = NULL,
high_eqbound = NULL,
alpha = NULL,
power = NULL,
type = "two.sample"
)
```

## Arguments

- n
number of observations per group. 2 sample sizes, in a vector, can be provided for the two sample case.

- delta
true difference in means (default is 0).

- sd
population standard deviation. Standard deviation of the differences for paired samples.

- eqb
Equivalence bound. Can provide 1 value (negative value is taken as the lower bound) or 2 specific values that represent the upper and lower equivalence bounds.

- low_eqbound
Lower equivalence bounds. Deprecated use eqb.

- high_eqbound
Upper equivalence bounds. Deprecated use eqb.

- alpha
a priori alpha-level (i.e., significance level).

- power
power of the TOST procedure (1-beta).

- type
string specifying the type of t-test.

## Details

The exact calculations of power are based on Owen’s Q-function or by direct integration of the bivariate non-central t-distribution (inspired by the PowerTOST package).
Approximate power is implemented via the non-central t-distribution or the ‘shifted’ central t-distribution.

## Note

The power function in this package is limited. Please see the PowerTOST R package for more options.

## References

Phillips KF. Power of the Two One-Sided Tests Procedure in Bioequivalence. J Pharmacokin Biopharm. 1990;18(2):137–44. doi: 10.1007/BF01063556

Diletti D, Hauschke D, Steinijans VW. Sample Size Determination for Bioequivalence Assessment by Means of Confidence Intervals. Int J Clin Pharmacol Ther Toxicol. 1991;29(1):1–8.