calc_contrast {cofad} | R Documentation |

## Calculate contrast analysis for factorial designs

### Description

Calculate contrast analysis for factorial designs

### Usage

```
calc_contrast(
dv,
between = NULL,
lambda_between = NULL,
within = NULL,
lambda_within = NULL,
ID = NULL,
id = NULL,
data = NULL
)
```

### Arguments

`dv` |
dependent variable. Values must be numeric. |

`between` |
independent variable that divides the data into independent groups. Vector must be a factor. |

`lambda_between` |
contrast weights must be a named numeric.
Names must match the levels of |

`within` |
independent variable which divides the data into dependent groups. This must be a factor. |

`lambda_within` |
contrast must be a named numeric.
Names must match the levels of |

`ID` |
deprecated, use id instead |

`id` |
identifier for cases or subjects is needed for within- and mixed contrast analysis. |

`data` |
optional argument for the |

### Details

For multi-factorial designs, the lambda weights of the factors must be connected.

Note that cofad returns one-sided p-values for t-tests.

### Value

an object of type cofad_bw or cofad_wi or cofad_mx, including p-value, F-value, contrast weights, different effect sizes. Call summary on this object to get a nice overview of all relevant statistics. Call print to get a short text that can be used for a report.

### References

Rosenthal, R., Rosnow, R.L., & Rubin, D.B. (2000). Contrasts and effect sizes in behavioral research: A correlational approach. New York: Cambridge University Press.

### Examples

```
# Example for between-subjects design Table 3.1 from
# Rosenthal, Rosnow and Rubin (2001)
data(rosenthal_tbl31)
contr_bw <- calc_contrast(
dv = dv,
between = between,
lambda_between = c("A" = -3, "B" = -1, "C" = 1, "D" = 3),
data = rosenthal_tbl31)
contr_bw
summary(contr_bw)
# Example for within-subjects design Calculation 16.6 from
# Sedlmeier and Renkewitz (2018, p. 537)
data(sedlmeier_p537)
contr_wi <- calc_contrast(
dv = reading_test,
within = music,
id = participant,
lambda_within = c(
"without music" = 1.25,
"white noise" = 0.25,
"classic" = -0.75,
"jazz" = -0.75
),
data = sedlmeier_p537
)
contr_wi
summary(contr_wi, ci = .90)
# Example for mixed-design Table 5.3 from
# Rosenthal, Rosnow and Rubin (2001)
data(rosenthal_tbl53)
contr_mx <- calc_contrast(dv = dv, between = between,
lambda_between = c("age8" = -1, "age10" = 0, "age12" = 1),
within = within,
lambda_within = c("1" = -3, "2" = -1,"3" = 1, "4" = 3),
id = id, data = rosenthal_tbl53
)
contr_mx
summary(contr_mx)
```

*cofad*version 0.3.0 Index]