CI.mean: Confidence intervals for the mean

In UBStats: Basic Statistics

Confidence intervals for the mean

Description

CI.mean() builds confidence intervals for the mean of a population.

Usage

CI.mean(
  x,
  sigma = NULL,
  conf.level = 0.95,
  digits = 2,
  force.digits = FALSE,
  use.scientific = FALSE,
  data,
  ...
)

Arguments

x	An unquoted string identifying the numeric variable whose mean is of interest. x can be the name of a vector in the workspace or the name of one of the columns in the data frame specified in the data argument.
sigma	An optional numeric value specifying the population standard deviation. If NULL (default) the population standard deviation is estimated using the data.
conf.level	Numeric value specifying the required confidence level; default to 0.95.
digits	Integer value specifying the number of decimals used to round statistics; default to 2. If the chosen rounding formats some non-zero values as zero, the number of decimals is increased so that all values have at least one significant digit, unless the argument force.digits is set to TRUE.
force.digits	Logical value indicating whether reported values should be forcedly rounded to the number of decimals specified in digits even if non-zero values are rounded to zero (default to FALSE).
use.scientific	Logical value indicating whether numbers in tables should be displayed using scientific notation (TRUE); default to FALSE.
data	An optional data frame containing x. If not found in data, x is taken from the environment from which CI.mean() is called.
...	Additional arguments to be passed to low level functions.

Value

A table reporting the confidence interval for the population mean. If the variance is unknown, the interval is built using percentiles from both the normal and the Student's t distribution.

Author(s)

Raffaella Piccarreta [e-mail]

See Also

TEST.mean() to test hypotheses on a population mean.

Examples

data(MktDATA, package = "UBStats")

# CI for the mean with KNOWN variance; default options
CI.mean(AOV, sigma = 30, data = MktDATA)

# CI for the mean with UNKNOWN variance;  
# - change digits and confidence level 0.99
CI.mean(AOV, conf.level = 0.99, digits = 3, data = MktDATA)

# Arguments force.digits and use.scientific
#  A variable taking very small values
SmallX<-MktDATA$AOV/5000 
#  - Default: manages possible excess of rounding
CI.mean(SmallX)
#  - Forcing digits to the default values (2)
CI.mean(SmallX, force.digits = TRUE)
#  - Allow scientific notation
CI.mean(SmallX, use.scientific = TRUE)

# Output the table with the requested interval
out.ci_mean<-CI.mean(AOV, data = MktDATA)

UBStats documentation built on Sept. 11, 2024, 6:52 p.m.