chisq_test_odds: Chi-square Test Sample Size Given Odds Ratio

In wikimedia/wikimedia-discovery-wmf: R Tools For Wikimedia Foundation's Analysts And Data Scientists

Description

Calculates sample size for chi-squared test of independence given the odds ratio.

Usage

chisq_test_odds(
  odds_ratio = NULL,
  p_control = NULL,
  p_treatment = NULL,
  power = NULL,
  conf_level = 0.95,
  sample_ratio = 1,
  visualize = FALSE
)

Arguments

odds_ratio	The expected odds ratio. That is, the ratio of the odds of the outcome in the test group relative to the control group. Optional, but see Details.
p_control	Your guess for prevalence of outcome in the control group. Optional but see Details.
p_treatment	Your guess for prevalence of outcome in the test group. Optional but see Details.
power	The ability of the test to detect an effect where there is one. Power = 1 - Prob(Type 2 error). Optional. See Value for details.
conf_level	Desired confidence level. Defaults to 95%.
sample_ratio	Ratio of test group to control group. 1 is even split.
visualize	Whether to plot power or prevalence of outcome in the control group vs sample size. Can be used to help make a decision.

Value

If power was not provided, returns vector containing possible power values and the appropriate sample size for each %. If all values were provided, returns a single sample size estimate.

Details

The function only needs to know two of the following three: odds_ratio, p_control, and p_treatment. If given all three, it will check to make sure the odds ratio is correct. It will figure out the missing third value from the other two.

References

Wang, H., Chow, S.-C., & Li, G. (2002). On sample size calculation based on odds ratio in clinical trials. Journal of Biopharmaceutical Statistics, 12(4), 471-483. doi:10.1081/BIP-120016231

Author(s)

Mikhail Popov

See Also

chisq_test_effect()

Examples

chisq_test_odds(p_treatment = 0.4, p_control = 0.25, power = 0.8)
chisq_test_odds(odds_ratio = 2, p_control = 0.4, power = c(0.8, 0.9, 0.95))
chisq_test_odds(odds_ratio = 2, p_control = 0.4)
chisq_test_odds(odds_ratio = 2, p_control = 0.4, visualize = TRUE)

wikimedia/wikimedia-discovery-wmf documentation built on Feb. 7, 2021, 12:19 a.m.