es_from_student_t_pval function

Convert a Student's t-test p-value to several effect size measures

es_from_student_t_pval(
  student_t_pval,
  n_exp,
  n_nexp,
  smd_to_cor = "viechtbauer",
  reverse_student_t_pval
)

Arguments

• student_t_pval: p-value (two-tailed) from a Student's t-test. If your p-value is one-tailed, simply multiply it by two.
• n_exp: number of participants in the experimental/exposed group.
• n_nexp: number of participants in the non-experimental/non-exposed group.
• smd_to_cor: formula used to convert the student_t_pval value into a coefficient correlation (see details).
• reverse_student_t_pval: a logical value indicating whether the direction of generated effect sizes should be flipped.

Returns

This function estimates and converts between several effect size measures.

natural effect size measure	D + G
converted effect size measure	OR + R + Z
required input data	See 'Section 11. ANOVA statistics, Student's t-test, or point-bis correlation'
	https://metaconvert.org/html/input.html

Details

This function converts the Student's t-test p-value into a t-value, and then relies on the calculations of the es_from_student_t() function.

To convert the p-value into a t-value, the following formula is used (table 12.1 in Cooper):

$$student\_t = qt(\frac{student\_t\_pval}{2}, df = n\_exp + n\_nexp - 2)$$

Then, calculations of the es_from_student_t() are applied.

Examples

es_from_student_t_pval(student_t_pval = 0.24, n_exp = 20, n_nexp = 22)

References

Cooper, H., Hedges, L.V., & Valentine, J.C. (Eds.). (2019). The handbook of research synthesis and meta-analysis. Russell Sage Foundation.