** LikertMakeR** synthesises Likert scale and
related rating-scale data. Such scales are constrained by upper and
lower bounds and discrete increments.

The package is intended for

“reproducing” rating-scale data for further analysis and visualisation when only summary statistics have been reported,

Teaching. Helping researchers and students to better understand the relationships among scale properties, sample size, number of items, etc..

Checking the feasibility of scale moments with given scale and correlation properties

Functions in ** LikertMakeR** are:

draws a random sample from a scaled*lfast()**Beta*distribution to approximate predefined first and second momentsattempts to produce a vector with exact first and second moments*lexact()*rearranges the values in the columns of a data set so that they are correlated to match a predefined correlation matrix*lcor()*

A Likert scale is the mean, or sum, of several ordinal rating scales. They are bipolar (usually “agree-disagree”) responses to propositions that are determined to be moderately-to-highly correlated and capturing various facets of a construct.

Rating scales are not continuous or unbounded.

For example, a 5-point Likert scale that is constructed with, say, five items (questions) will have a summed range of between 5 (all rated ‘1’) and 25 (all rated ‘5’) with all integers in between, and the mean range will be ‘1’ to ‘5’ with intervals of 1/5=0.20. A 7-point Likert scale constructed from eight items will have a summed range between 8 (all rated ‘1’) and 56 (all rated ‘7’) with all integers in between, and the mean range will be ‘1’ to ‘7’ with intervals of 1/8=0.125.

Typically, a researcher will synthesise rating-scale data by sampling with a predetermined probability distribution. For example, the following code will generate a vector of values with approximately the given probabilities.

```{r, eval = FALSE}

`n <- 128 sample(1:5, n, replace = TRUE, prob = c(0.1, 0.2, 0.4, 0.2, 0.1) )`

```

The functions `lfast()`

and `lexact()`

allow
the user to specify exact univariate statistics as they might ordinarily
be reported.

The development version of ** LikertMakeR** is
available from the author’s GitHub repository.

To download and install the package, run the following code from your R console:

```{r, eval=FALSE}

library(devtools) install_github(“WinzarH/LikertMakeR”)

```

To synthesise a rating scale, the user must input the following parameters:

: sample size*n*: desired mean*mean*: desired standard deviation*sd*: desired lower bound*lowerbound*: desired upper bound*upperbound*: number of items making the scale - default = 1*items*: optional seed for reproducibility*seed*offers two different functions for synthesising a rating scale:*LikertMakeR*and*lfast()**lexact()*

draws a random sample from a scaled*lfast()**Beta*distribution. It is very fast but does not guarantee that the mean and standard deviation are exact. Recommended for relatively large sample sizes.

Example: a five-item, seven-point Likert scale

`x <- lfast( n = 256, mean = 4.5, sd = 1.0, lowerbound = 1, upperbound = 7, items = 5 )`

Example: an 11-point likelihood-of-purchase scale

`x <- lfast(256, 2.5, 2.5, 0, 10)`

attempts to produce a vector with exact first and second moments. It uses the*lexact()**Differential Evolution*algorithm in the ‘DEoptim’ package to find appropriate values within the desired constraints.

** lexact()** may take some time to complete the
optimisation task, but is excellent for simulating data from
already-published reports where only summary statistics are
reported.

Example: a five-item, seven-point Likert scale

`x <- lexact( n = 32, mean = 4.5, sd = 1.0, lowerbound = 1, upperbound = 7, items = 5 )`

Example: an 11-point likelihood-of-purchase scale

`x <- lexact(32, 2.5, 2.5, 0, 10)`

Example: a seven-point negative-to-positive scale with 4 items

`x <- lexact( n = 32, mean = 1.25, sd = 1.00, lowerbound = -3, upperbound = 3, items = 4 )`

** LikertMakeR** offers another function,

To create the desired correlations, the user must define the following objects:

: a starter data set of rating-scales*data*: the target correlation matrix*target*

`set.seed(42) # for reproducibility n <- 64 x1 <- lfast(n, 3.5, 1.00, 1, 5, 5) x2 <- lfast(n, 1.5, 0.75, 1, 5, 5) x3 <- lfast(n, 3.0, 1.70, 1, 5, 5) x4 <- lfast(n, 2.5, 1.50, 1, 5, 5) mydat4 <- cbind(x1, x2, x3, x4) |> data.frame() head(mydat4) cor(mydat4) |> round(3)`

`tgt4 <- matrix( c( 1.00, 0.50, 0.50, 0.75, 0.50, 1.00, 0.25, 0.65, 0.50, 0.25, 1.00, 0.80, 0.75, 0.65, 0.80, 1.00 ), nrow = 4 )`

`new4 <- lcor(data = mydat4, target = tgt4) cor(new4) |> round(3)`

`mydat3 <- cbind(x1, x2, x3) |> data.frame() tgt3 <- matrix( c( 1.00, -0.50, -0.85, -0.50, 1.00, 0.60, -0.85, 0.60, 1.00 ), nrow = 3 ) new3 <- lcor(mydat3, tgt3) cor(new3) |> round(3)`

here’s how to cite this package:

`Winzar, H. (2022). LikertMakeR: Synthesise and correlate rating-scale data with predefined first & second moments, <https://github.com/WinzarH/LikertMakeR>`