## Objects from the Class

Objects can be created by calls of the form `new("splineMatrix", ...)`

, but this is not encouraged. Previously produced coefficient matrices MUST be bound to the IDENTICAL knots and boundaries used to create them. Use the function `studentGrowthPercentiles`

instead.

## Slots

`.Data`

:A coefficient matrix derived from `studentGrowthPercentiles`

.

`Knots`

:A list(s) of numeric values used as the `knots`

to generate the B-spline basis matrix in `studentGrowthPercentiles`

.

`Boundaries`

:A list(s) of numeric values used as the `Boundary.knots`

to generate the B-spline basis matrix in `studentGrowthPercentiles`

.

`Content_Areas`

:A list of time dependent content area names included in the data used to produce the coefficient matrix.

`Grade_Progression`

:A list of the time dependent grades included in the data used to produce matrices.

`Time`

:A list of the Times (e.g., years) measurements occurred included in the data used to produce matrices.

`Time_Lags`

:A list of the time lags/differences between Time (e.g., years) included in the data used to produce matrices.

`Version`

:A list including the version of the SGP package used to construct the splineMatrix object and the date the object was created.

## Details

- splineMatrix:
This class contains the S3 `matrix`

class, inheriting its methods. The slot `Knots`

should be one or more lists of numeric vector(s) used in the internal call
to `bs`

, which generates a B-spline basis matrix from student scores. There are typically with 4 values for the knots. Similarly, `Boundaries`

are used in `bs`

for the
`Boundary.knots`

argument. This is always two values which are at or slightly beyond the lowest and highest observed student scores. `Content_Areas`

and
`Grade_Progression`

provide information about the data (sub)set used to produce the matrix.

## See also

`studentGrowthPercentiles`