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grafify (version 5.0.0)

simple_model: Model from a linear model fit to data.

Description

One of two functions for simple ANOVA tables and linear models without random effects, which use lm to fit a linear models.

  1. link{simple_anova}

  2. link{simple_model}

Usage

simple_model(data, Y_value, Fixed_Factor, ...)

Value

This function returns an object of class "lm".

Arguments

data

a data table object, e.g. data.frame or tibble.

Y_value

name of column containing quantitative (dependent) variable, provided within "quotes". The following transformations are permitted: "log(Y_value)", "log(Y_value + c)" where c a positive number, "logit(Y_value)" or "logit(Y_value/100)" which may be useful when Y_value are percentages (note quotes outside the log or logit calls); "sqrt(Y_value)" or "(Y_value)^2" should also work. During posthoc-comparisons, log and logit transformations will be back-transformed to the original scale. Other transformations, e.g., "sqrt(Y_value)" will not be back-transformed. Check out the regrid and ref_grid for details if you need back-transformation to the response scale.

Fixed_Factor

name(s) of categorical fixed factors (independent variables) provided within quotes (e.g., "A") or as a vector if more than one (e.g., c("A", "B"). If a numeric variable(s) is used, transformations similar to Y_value are permitted.

...

any additional arguments to pass on to lm if required.

Details

Update in v0.2.1: This function uses lm to fit a linear model to data, passes it on to Anova, and outputs the ANOVA table with type II sum of squares with F statistics and P values.

(Previous versions produced type I sum of squares using anova call.) It requires a data table, one quantitative dependent variable and one or more independent variables.

The model output can be used to extract coefficients and other information, including post-hoc comparisons. If your experiment design has random factors, use the related function mixed_model.

This function is related to link{simple_anova}. Output of this function can be used with posthoc_Pairwise, posthoc_Levelwise and posthoc_vsRef, or with emmeans.

Examples

Run this code
#fixed factors provided as a vector
Doubmodel <- simple_model(data = data_doubling_time,
Y_value =  "Doubling_time", 
Fixed_Factor = "Student")
#get summary
summary(Doubmodel)

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