Description Usage Arguments Details Value References See Also Examples

View source: R/est_typing_err.R

Estimates the Expected Number of Errors in a Data Entry Job

1 | ```
est_typing_err(S, F, prior = "postmen", quantity = "mean")
``` |

`S` |
size of the evaluation sample |

`F` |
number of errors in the evaluation sample |

`prior` |
can be either 'postmen', 'bad_postmen' or a named vector with prior values. See below for details. |

`quantity` |
can be either 'mean', '95q' or 'param'. See below for details. |

The function calcualtes (Bayesian posterior) estimates for the expected number of errors (`quantity='mean'`

) or the
upper bound of the 95% (Bayesian) credible interval (`quantity='95q'`

) in the population of entered values when a
random sample of `S`

entered values contains `F`

errors. For a discussion on the type of inference, see Winkler
et al. (2002).

The calculations are done assuming a Beta-distribution prior over the proportion of errors for all entered values. The users must supply hyper-parameters for the Beta-prior. The function provides two informed default hyper-parameter sets. Both induce an informed prior and are formed from data about postmen's performance in typing post codes as reported in Baddeley/Longman (1978).

The first prior (`prior='postmen'`

) says that the a-priori the proportion of errors relative to the total number of entered
values is about 1.4% with a variance 0.7. The second prior (`prior='bad_postmen'`

) is more conservative saying that
it is about 2.1% with a variance of 1.1. Users can also supply their own prior using a named vector that contains the alpha
and beta hyper-parameters for the Beta prior (the output of `calc_beta_param`

can be used).

value or vector of the requested quanty/ies.

Baddeley, A. D., and D. J. A. Longman. 1978. "The influence of length and frequency of training session on the rate of learning to type." Ergonomics 21(8), 627-635.

Winkler, Robert L. and Smith, James E. and Fryback, Dennis G. 2002. "The Role of Informative Priors in Zero-Numerator Problems: Being Conservative Versus Being Candid". The American Statistician 56(1), 1-4.

1 2 3 4 5 6 7 8 9 10 | ```
## Not run:
est_typing_err(S=20, F=0, prior='postmen', quantity='95q')
Example from Winkler et al. (2002) p.3:
est_typing_err(167, 0, prior=c('alpha'=0.042, 'beta'=27.96), quantity='param' )
## End(Not run)
``` |

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