ReadingSkills {bayesbr} | R Documentation |

## Dyslexia and IQ Predicting Reading Accuracy

### Description

Data to verify the importance of non-verbal IQ in children's reading skills in dyslexic and non-dyslexic children.

### Usage

data("ReadingSkills")

### Format

A data frame containing 44 observations on 3 variables.

- accuracy
reading score scaled to the open unit interval (see below).

- dyslexia
Is the child dyslexic? If 0, no; If 1, yes.

- iq
non-verbal intelligence quotient transformed to z-scores.

### Details

The data were collected by Pammer and Kevan (2004). The original precision score was transformed by Smithson and Verkuilen (2006) so that the values of `precision`

are always between 0 to 1, enabling the use of beta regression.

First, the original accuracy was scaled using the minimal and maximal score (`a`

and `b`

, respectively) that can be obtained in the test: `(original_accuracy - a) / (b - a)`

(`a`

and `b`

are not provided). Subsequently, the scaled score is transformed to the unit interval using a continuity correction: `(scaled_accuracy * (n-1) - 0.5) / n`

(either with some rounding or using `n = 50`

rather than 44).

The `dyslexia`

variable that was a qualitative variable was transformed into a quantitative variable to be used by the package functions.

### Source

Example 3 from Smithson and Verkuilen (2006) supplements.

### References

doi: 10.18637/jss.v034.i02 Cribari-Neto, F., and Zeileis, A. (2010). Beta Regression in R.
*Journal of Statistical Software*, **34**(2), 1–24.
https://www.jstatsoft.org/article/view/v034i02.

doi: 10.18637/jss.v048.i11 GrĂ¼n, B., Kosmidis, I., and Zeileis, A. (2012).
Extended Beta Regression in R: Shaken, Stirred, Mixed, and Partitioned.
*Journal of Statistical Software*, **48**(11), 1–25.
https://www.jstatsoft.org/article/view/v048i11.

doi: 10.1080/10888430709336633 Pammer, K., and Kevan, A. (2004).
The Contribution of Visual Sensitivity, Phonological Processing
and Non-Verbal IQ to Children's Reading.
*Unpublished manuscript*, The Australian National University, Canberra.

doi: 10.1037/1082-989X.11.1.54 Smithson, M., and Verkuilen, J. (2006).
A Better Lemon Squeezer? Maximum-Likelihood Regression with
Beta-Distributed Dependent Variables.
*Psychological Methods*, **11**(7), 54–71.

### Examples

data("ReadingSkills", package = "bayesbr")
bbr = bayesbr(accuracy~iq+dyslexia, iter=1000,warmup=300,
data=ReadingSkills)
summary(bbr)

[Package

*bayesbr* version 0.0.1.0

Index]