The package require all variables to be numerical. So a multi-categorical factor needs to be converted to dummy variables or multiple dichotomous indicators. For survival outcome models, the indicator variable is for the event (1 = event, 0 = censored).
regmedint
objectFollowing typical modeling workflow in R (e.g., lm
and
glm
), a constructor function is used to create a model fit
object. The summary
method is the main user function for
examining the results in the object. Lower-level methods such as
coef
, vcov
, and confint
are also
provided for flexibility. The print
method is mainly for
meaningful implicit printing when only the object name is evaluated. All
methods for the regmedint
object has arguments
a0
, a1
, m_cde
, and
c_cond
. These are used to re-evaluate the results without
re-fitting the underlying models.
regemedint()
object constructorregmedint_obj <- regmedint(data = vv2015,
## Variables
yvar = "y",
avar = "x",
mvar = "m",
cvar = c("c"),
eventvar = "event",
## Values at which effects are evaluated
a0 = 0,
a1 = 1,
m_cde = 1,
c_cond = 0.5,
## Model types
mreg = "logistic",
yreg = "survAFT_weibull",
## Additional specification
interaction = TRUE,
casecontrol = FALSE)
summary()
for regmedint
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.541070807 0.29422958 1.8389409 0.06592388 -0.03560858 1.11775019
## pnde 0.488930417 0.21049248 2.3227928 0.02019028 0.07637274 0.90148809
## tnie 0.018240025 0.03706111 0.4921608 0.62260566 -0.05439841 0.09087846
## tnde 0.498503455 0.21209540 2.3503737 0.01875457 0.08280410 0.91420281
## pnie 0.008666987 0.02730994 0.3173565 0.75097309 -0.04485951 0.06219348
## te 0.507170442 0.21090051 2.4047853 0.01618197 0.09381303 0.92052785
## pm 0.045436278 0.09119614 0.4982259 0.61832484 -0.13330488 0.22417743
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 1
## cvar: c
## c_cond (covariate vector value) = 0.5
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.541070807 0.29422958 1.8389409 0.06592388 -0.03560858 1.11775019
## pnde 0.488930417 0.21049248 2.3227928 0.02019028 0.07637274 0.90148809
## tnie 0.018240025 0.03706111 0.4921608 0.62260566 -0.05439841 0.09087846
## tnde 0.498503455 0.21209540 2.3503737 0.01875457 0.08280410 0.91420281
## pnie 0.008666987 0.02730994 0.3173565 0.75097309 -0.04485951 0.06219348
## te 0.507170442 0.21090051 2.4047853 0.01618197 0.09381303 0.92052785
## pm 0.045436278 0.09119614 0.4982259 0.61832484 -0.13330488 0.22417743
## exp(est) exp(lower) exp(upper)
## cde 1.717845 0.9650179 3.057967
## pnde 1.630571 1.0793648 2.463266
## tnie 1.018407 0.9470547 1.095136
## tnde 1.646256 1.0863290 2.494786
## pnie 1.008705 0.9561318 1.064168
## te 1.660586 1.0983544 2.510615
## pm NA NA NA
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 1
## cvar: c
## c_cond (covariate vector value) = 0.5
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.440756562 0.30083077 1.4651313 0.14288511 -0.14886090 1.03037403
## pnde 0.492306223 0.21015655 2.3425690 0.01915149 0.08040695 0.90420550
## tnie 0.018077074 0.03653416 0.4947991 0.62074191 -0.05352857 0.08968272
## tnde 0.501765186 0.21433402 2.3410432 0.01922994 0.08167823 0.92185214
## pnie 0.008618111 0.02707487 0.3183067 0.75025232 -0.04444765 0.06168388
## te 0.510383297 0.21212172 2.4060870 0.01612443 0.09463237 0.92613422
## pm 0.044816400 0.08889613 0.5041434 0.61416060 -0.12941682 0.21904962
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 0
## cvar: c
## c_cond (covariate vector value) = 1
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.440756562 0.30083077 1.4651313 0.14288511 -0.33413214 1.21564526
## pnde 0.492306223 0.21015655 2.3425690 0.01915149 -0.04902118 1.03363363
## tnie 0.018077074 0.03653416 0.4947991 0.62074191 -0.07602870 0.11218285
## tnde 0.501765186 0.21433402 2.3410432 0.01922994 -0.05032266 1.05385303
## pnie 0.008618111 0.02707487 0.3183067 0.75025232 -0.06112213 0.07835835
## te 0.510383297 0.21212172 2.4060870 0.01612443 -0.03600604 1.05677263
## pm 0.044816400 0.08889613 0.5041434 0.61416060 -0.18416486 0.27379767
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 0
## cvar: c
## c_cond (covariate vector value) = 1
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.
coef()
for regmedint
## cde pnde tnie tnde pnie te
## 0.541070807 0.488930417 0.018240025 0.498503455 0.008666987 0.507170442
## pm
## 0.045436278
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 1
##
## attr(,"args")$c_cond
## [1] 0.5
## cde pnde tnie tnde pnie te
## 0.440756562 0.492306223 0.018077074 0.501765186 0.008618111 0.510383297
## pm
## 0.044816400
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 0
##
## attr(,"args")$c_cond
## [1] 1
vcov()
for regmedint
## cde pnde tnie tnde pnie te
## cde 0.08657105 NA NA NA NA NA
## pnde NA 0.04430708 NA NA NA NA
## tnie NA NA 0.001373526 NA NA NA
## tnde NA NA NA 0.04498446 NA NA
## pnie NA NA NA NA 0.0007458327 NA
## te NA NA NA NA NA 0.04447903
## pm NA NA NA NA NA NA
## pm
## cde NA
## pnde NA
## tnie NA
## tnde NA
## pnie NA
## te NA
## pm 0.008316736
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 1
##
## attr(,"args")$c_cond
## [1] 0.5
## cde pnde tnie tnde pnie te
## cde 0.09049915 NA NA NA NA NA
## pnde NA 0.04416578 NA NA NA NA
## tnie NA NA 0.001334745 NA NA NA
## tnde NA NA NA 0.04593907 NA NA
## pnie NA NA NA NA 0.0007330485 NA
## te NA NA NA NA NA 0.04499562
## pm NA NA NA NA NA NA
## pm
## cde NA
## pnde NA
## tnie NA
## tnde NA
## pnie NA
## te NA
## pm 0.007902522
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 0
##
## attr(,"args")$c_cond
## [1] 1
confint()
for regmedint
## lower upper
## cde -0.03560858 1.11775019
## pnde 0.07637274 0.90148809
## tnie -0.05439841 0.09087846
## tnde 0.08280410 0.91420281
## pnie -0.04485951 0.06219348
## te 0.09381303 0.92052785
## pm -0.13330488 0.22417743
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 1
##
## attr(,"args")$c_cond
## [1] 0.5
## lower upper
## cde -0.14886090 1.03037403
## pnde 0.08040695 0.90420550
## tnie -0.05352857 0.08968272
## tnde 0.08167823 0.92185214
## pnie -0.04444765 0.06168388
## te 0.09463237 0.92613422
## pm -0.12941682 0.21904962
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 0
##
## attr(,"args")$c_cond
## [1] 1
## lower upper
## cde -0.33413214 1.21564526
## pnde -0.04902118 1.03363363
## tnie -0.07602870 0.11218285
## tnde -0.05032266 1.05385303
## pnie -0.06112213 0.07835835
## te -0.03600604 1.05677263
## pm -0.18416486 0.27379767
## attr(,"args")
## attr(,"args")$a0
## [1] 0
##
## attr(,"args")$a1
## [1] 1
##
## attr(,"args")$m_cde
## [1] 0
##
## attr(,"args")$c_cond
## [1] 1
print()
for regmedint
## ### Mediator model
##
## Call: glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## (Intercept) x c
## -0.3545 0.3842 0.2694
##
## Degrees of Freedom: 99 Total (i.e. Null); 97 Residual
## Null Deviance: 138.6
## Residual Deviance: 136.1 AIC: 142.1
## ### Outcome model
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
##
## Coefficients:
## (Intercept) x m c x:m
## -1.04244118 0.44075656 0.09053705 -0.06689165 0.10031424
##
## Scale= 0.9658808
##
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.177
## n= 100
## ### Mediation analysis
## cde pnde tnie tnde pnie te
## 0.541070807 0.488930417 0.018240025 0.498503455 0.008666987 0.507170442
## pm
## 0.045436278
## ### Mediator model
##
## Call: glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## (Intercept) x c
## -0.3545 0.3842 0.2694
##
## Degrees of Freedom: 99 Total (i.e. Null); 97 Residual
## Null Deviance: 138.6
## Residual Deviance: 136.1 AIC: 142.1
## ### Outcome model
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
##
## Coefficients:
## (Intercept) x m c x:m
## -1.04244118 0.44075656 0.09053705 -0.06689165 0.10031424
##
## Scale= 0.9658808
##
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.177
## n= 100
## ### Mediation analysis
## cde pnde tnie tnde pnie te
## 0.541070807 0.488930417 0.018240025 0.498503455 0.008666987 0.507170442
## pm
## 0.045436278
## ### Mediator model
##
## Call: glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## (Intercept) x c
## -0.3545 0.3842 0.2694
##
## Degrees of Freedom: 99 Total (i.e. Null); 97 Residual
## Null Deviance: 138.6
## Residual Deviance: 136.1 AIC: 142.1
## ### Outcome model
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
##
## Coefficients:
## (Intercept) x m c x:m
## -1.04244118 0.44075656 0.09053705 -0.06689165 0.10031424
##
## Scale= 0.9658808
##
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.177
## n= 100
## ### Mediation analysis
## cde pnde tnie tnde pnie te
## 0.440756562 0.492306223 0.018077074 0.501765186 0.008618111 0.510383297
## pm
## 0.044816400
summary_regmedint
The summary
method for the regmedint
object
returns an object of class summary_regmedint
. To extract
the mediation analysis result table as a matrix, use the
coef
method.
coef()
for summary_regmedint
## est se Z p lower upper
## cde 0.541070807 0.29422958 1.8389409 0.06592388 -0.03560858 1.11775019
## pnde 0.488930417 0.21049248 2.3227928 0.02019028 0.07637274 0.90148809
## tnie 0.018240025 0.03706111 0.4921608 0.62260566 -0.05439841 0.09087846
## tnde 0.498503455 0.21209540 2.3503737 0.01875457 0.08280410 0.91420281
## pnie 0.008666987 0.02730994 0.3173565 0.75097309 -0.04485951 0.06219348
## te 0.507170442 0.21090051 2.4047853 0.01618197 0.09381303 0.92052785
## pm 0.045436278 0.09119614 0.4982259 0.61832484 -0.13330488 0.22417743
print()
for summary_regmedint
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.541070807 0.29422958 1.8389409 0.06592388 -0.03560858 1.11775019
## pnde 0.488930417 0.21049248 2.3227928 0.02019028 0.07637274 0.90148809
## tnie 0.018240025 0.03706111 0.4921608 0.62260566 -0.05439841 0.09087846
## tnde 0.498503455 0.21209540 2.3503737 0.01875457 0.08280410 0.91420281
## pnie 0.008666987 0.02730994 0.3173565 0.75097309 -0.04485951 0.06219348
## te 0.507170442 0.21090051 2.4047853 0.01618197 0.09381303 0.92052785
## pm 0.045436278 0.09119614 0.4982259 0.61832484 -0.13330488 0.22417743
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 1
## cvar: c
## c_cond (covariate vector value) = 0.5
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.
## ### Mediator model
##
## Call:
## glm(formula = m ~ x + c, family = binomial(link = "logit"), data = data)
##
## Coefficients:
## Estimate Std. Error z value Pr(>|z|)
## (Intercept) -0.3545 0.3252 -1.090 0.276
## x 0.3842 0.4165 0.922 0.356
## c 0.2694 0.2058 1.309 0.191
##
## (Dispersion parameter for binomial family taken to be 1)
##
## Null deviance: 138.59 on 99 degrees of freedom
## Residual deviance: 136.08 on 97 degrees of freedom
## AIC: 142.08
##
## Number of Fisher Scoring iterations: 4
##
## ### Outcome model
##
## Call:
## survival::survreg(formula = Surv(y, event) ~ x + m + x:m + c,
## data = data, dist = "weibull")
## Value Std. Error z p
## (Intercept) -1.0424 0.1903 -5.48 4.3e-08
## x 0.4408 0.3008 1.47 0.14
## m 0.0905 0.2683 0.34 0.74
## c -0.0669 0.0915 -0.73 0.46
## x:m 0.1003 0.4207 0.24 0.81
## Log(scale) -0.0347 0.0810 -0.43 0.67
##
## Scale= 0.966
##
## Weibull distribution
## Loglik(model)= -11.4 Loglik(intercept only)= -14.5
## Chisq= 6.31 on 4 degrees of freedom, p= 0.18
## Number of Newton-Raphson Iterations: 5
## n= 100
##
## ### Mediation analysis
## est se Z p lower upper
## cde 0.541070807 0.29422958 1.8389409 0.06592388 -0.03560858 1.11775019
## pnde 0.488930417 0.21049248 2.3227928 0.02019028 0.07637274 0.90148809
## tnie 0.018240025 0.03706111 0.4921608 0.62260566 -0.05439841 0.09087846
## tnde 0.498503455 0.21209540 2.3503737 0.01875457 0.08280410 0.91420281
## pnie 0.008666987 0.02730994 0.3173565 0.75097309 -0.04485951 0.06219348
## te 0.507170442 0.21090051 2.4047853 0.01618197 0.09381303 0.92052785
## pm 0.045436278 0.09119614 0.4982259 0.61832484 -0.13330488 0.22417743
##
## Evaluated at:
## avar: x
## a1 (intervened value of avar) = 1
## a0 (reference value of avar) = 0
## mvar: m
## m_cde (intervend value of mvar for cde) = 1
## cvar: c
## c_cond (covariate vector value) = 0.5
##
## Note that effect estimates can vary over m_cde and c_cond values when interaction = TRUE.