grail-codeocean-raw / code /gun control (issue 1) /03_analysis_multipletesting.R
Brandon Stewart
Version 1.0
649d4d3
cat(rep('=', 80),
'\n\n',
'OUTPUT FROM: gun control (issue 1)/03_analysis_multipletesting.R',
'\n\n',
sep = ''
)
library(data.table)
library(car)
library(sandwich)
library(lmtest)
library(ggplot2)
library(assertthat)
library(foreach)
library(doParallel)
registerDoParallel(cores = detectCores() - 1)
###############
## functions ##
###############
`%.%` <- paste0
simes <- function(ps){
min(sort(length(ps) * ps / rank(ps)))
}
### functions to handle inconsistent interaction ordering of mlm() ###
## convert interaction terms of form 'b#:a#' to 'a#:b#'
reorder.interaction.names <- function(x, prefix = ''){
x <- gsub('^' %.% prefix, '', x)
sapply(strsplit(x, ':'),
function(y){
paste(sort(y), collapse = ':')
})
}
## take term of form 'a1:b1', look up in vector of form 'b#:a#, return 'b1:a1'
convert.interaction.names <- function(x, y, prefix.y = ''){
ind <- match(reorder.interaction.names(x),
reorder.interaction.names(y, prefix = prefix.y)
)
return(y[ind])
}
## modified from print.linearHypothesis.mlm to use alternate df & return pvals
## (print method is responsible for doing the actual computation of pvals)
extract.lht <- function(x,
SSP = TRUE,
SSPE = SSP,
digits = getOption('digits'),
df.residual = x$df.residual
){
test <- x$test
if (!is.null(x$P) && SSP) {
P <- x$P
cat("\n Response transformation matrix:\n")
attr(P, "assign") <- NULL
attr(P, "contrasts") <- NULL
print(P, digits = digits)
}
if (SSP) {
cat("\nSum of squares and products for the hypothesis:\n")
print(x$SSPH, digits = digits)
}
if (SSPE) {
cat("\nSum of squares and products for error:\n")
print(x$SSPE, digits = digits)
}
if ((!is.null(x$singular)) && x$singular) {
warning("the error SSP matrix is singular; multivariate tests are unavailable")
return(invisible(x))
}
SSPE.qr <- qr(x$SSPE)
eigs <- Re(eigen(qr.coef(SSPE.qr, x$SSPH), symmetric = FALSE)$values)
tests <- matrix(NA, 4, 4)
rownames(tests) <- c("Pillai", "Wilks", "Hotelling-Lawley",
"Roy")
if ("Pillai" %in% test)
tests[1, 1:4] <- car:::Pillai(eigs, x$df, df.residual)
if ("Wilks" %in% test)
tests[2, 1:4] <- car:::Wilks(eigs, x$df, df.residual)
if ("Hotelling-Lawley" %in% test)
tests[3, 1:4] <- car:::HL(eigs, x$df, df.residual)
if ("Roy" %in% test)
tests[4, 1:4] <- car:::Roy(eigs, x$df, df.residual)
tests <- na.omit(tests)
ok <- tests[, 2] >= 0 & tests[, 3] > 0 & tests[, 4] > 0
ok <- !is.na(ok) & ok
tests <- cbind(x$df, tests, pf(tests[ok, 2], tests[ok, 3],
tests[ok, 4], lower.tail = FALSE))
colnames(tests) <- c("Df", "test stat", "approx F", "num Df",
"den Df", "Pr(>F)")
tests <- structure(as.data.frame(tests),
heading = paste("\nMultivariate Test",
if (nrow(tests) > 1)
"s", ": ", x$title, sep = ""),
class = c("anova",
"data.frame"
)
)
return(tests)
}
###############
## load data ##
###############
d <- fread('../results/intermediate data/gun control (issue 1)/guncontrol_qualtrics_w123_clean.csv')
## drop pure control
d <- d[treatment_arm != 'control',]
## drop NA video counts
d <- d[!is.na(pro) & !is.na(anti),]
##############
## controls ##
##############
platform.controls <- c('age_cat',
'male',
'pol_interest',
'freq_youtube',
'fav_channels',
'popular_channels',
'vid_pref',
'gun_enthusiasm',
'gun_importance'
)
gunpolicy.controls <- 'gun_index'
media.controls <- c('trust_majornews_w1',
'trust_youtube_w1',
'fabricate_majornews_w1',
'fabricate_youtube_w1'
)
affpol.controls <- c('affpol_ft',
'affpol_smart',
'affpol_comfort'
)
controls.raw <- unique(c(platform.controls,
gunpolicy.controls,
media.controls,
affpol.controls
)
)
## transform control variables by creating dummies and demeaning
controls.trans <- list()
for (j in controls.raw){
## convert to dummies if needed
controls.j <- model.matrix(as.formula('~ 0 + ' %.% j),
model.frame(as.formula('~ 0 + ' %.% j),
data = d,
na.action = 'na.pass'
)
)
## demean by column
controls.j <- sweep(controls.j,
MARGIN = 2,
STATS = colMeans(controls.j, na.rm = TRUE),
FUN = `-`,
)
colnames(controls.j) <- make.names(colnames(controls.j))
## remove control from original data
d[[j]] <- NULL
## reinsert transformed control
d <- cbind(d, controls.j)
## keep track of which original controls map to which transformed controls
controls.trans[[j]] <- colnames(controls.j)
}
## map original control variables to transformed versions
platform.controls <- unlist(controls.trans[platform.controls])
gunpolicy.controls <- unlist(controls.trans[gunpolicy.controls])
media.controls <- unlist(controls.trans[media.controls])
affpol.controls <- unlist(controls.trans[affpol.controls])
##############
## outcomes ##
##############
### hypothesis family 1: platform interactions ###
## platform interaction time: compute windorized usage time
warning('diverges from pap, 95% windsorized due to extreme outliers')
d[, platform_duration := duration]
d[platform_duration <= quantile(d$duration, .025),
platform_duration := quantile(d$duration, .025)
]
d[platform_duration >= quantile(d$duration, .975),
platform_duration := quantile(d$duration, .975)
]
## all platform interaction outcomes
platform.outcomes <- c('pro_fraction_chosen',
'positive_interactions', # positive - negative (dislike)
'platform_duration'
)
### hypothesis family 2: gun policy attitudes ###
## only one preregistered outcome in this family
gunpolicy.outcomes <- 'gun_index_w2'
## added 4 jun 2024 by reviewer request
gunpolicy.outcomes.understanding <- c('right_to_own_importance_w2',
'concealed_safe_w2'
)
### hypothesis family 3: media trust ###
media.outcomes <- c('trust_majornews_w2',
'trust_youtube_w2',
'fabricate_majornews_w2',
'fabricate_youtube_w2'
)
### hypothesis family 4: affective polarization ###
affpol.outcomes <- c('affpol_ft_w2',
'affpol_smart_w2',
'affpol_comfort_w2'
)
outcomes <- unique(c(platform.outcomes,
gunpolicy.outcomes,
media.outcomes,
affpol.outcomes
)
)
################
## treatments ##
################
## create attitude dummies
d[, attitude := c('anti', 'neutral', 'pro')[thirds]]
d[, attitude.anti := as.numeric(attitude == 'anti')]
d[, attitude.neutral := as.numeric(attitude == 'neutral')]
d[, attitude.pro := as.numeric(attitude == 'pro')]
## create seed dummies
d[, seed.anti := as.numeric(treatment_seed == 'anti')]
d[, seed.pro := as.numeric(treatment_seed == 'pro')]
## create recsys dummies
d[, recsys.22 := as.numeric(treatment_arm %like% '22')]
d[, recsys.31 := as.numeric(treatment_arm %like% '31')]
## manually define coefficients to estimate
treatments <- c('attitude.anti:recsys.22',
'attitude.anti:recsys.31',
'attitude.neutral:seed.anti:recsys.22',
'attitude.neutral:seed.pro:recsys.22',
'attitude.neutral:seed.anti:recsys.31',
'attitude.neutral:seed.pro:recsys.31',
'attitude.pro:recsys.22',
'attitude.pro:recsys.31'
)
contrasts <- rbind(
i = c(treat = 'attitude.pro:recsys.31',
ctrl = 'attitude.pro:recsys.22'
),
ii = c(treat = 'attitude.anti:recsys.31',
ctrl = 'attitude.anti:recsys.22'
),
iii = c(treat = 'attitude.neutral:seed.pro:recsys.31',
ctrl = 'attitude.neutral:seed.pro:recsys.22'
),
iv = c(treat = 'attitude.neutral:seed.anti:recsys.31',
ctrl = 'attitude.neutral:seed.anti:recsys.22'
),
v = c(treat = 'attitude.neutral:seed.pro:recsys.31',
ctrl = 'attitude.neutral:seed.anti:recsys.31'
),
vi = c(treat = 'attitude.neutral:seed.pro:recsys.22',
ctrl = 'attitude.neutral:seed.anti:recsys.22'
)
)
## check that contrasts are valid
assert_that(all(unlist(contrasts) %in% treatments))
## check that specifications are equivalent
coefs.v1 <- coef(lm(gun_index_w2 ~ 0 + attitude:treatment_arm, d))
coefs.v2 <- coef(
lm(gun_index_w2 ~
0 +
attitude.anti:recsys.22 +
attitude.anti:recsys.31 +
attitude.neutral:seed.anti:recsys.22 +
attitude.neutral:seed.pro:recsys.22 +
attitude.neutral:seed.anti:recsys.31 +
attitude.neutral:seed.pro:recsys.31 +
attitude.pro:recsys.22 +
attitude.pro:recsys.31,
d
)
)
assert_that(all.equal(unname(sort(coefs.v1)), unname(sort(coefs.v2))))
##########################
## hierarchical testing ##
##########################
## initialize top layer p-values:
## does treatment have any effect on any outcome in family
families <- c('platform',
'gunpolicy',
'media',
'affpol'
)
layer1.pvals <- rep(NA_real_, length(families))
layer1.notes <- rep('', length(families))
names(layer1.pvals) <- families
## initialize 2nd layer p-values:
## which treatment has detectable effect?
contrast.pvals <- rep(NA_real_, nrow(contrasts))
names(contrast.pvals) <- paste(contrasts[, 'treat'],
contrasts[, 'ctrl'],
sep = '.vs.'
)
layer2.pvals <- list(platform = contrast.pvals,
gunpolicy = contrast.pvals,
media = contrast.pvals,
affpol = contrast.pvals
)
rm(contrast.pvals)
## initialize 3rd layer p-values:
## on which specific outcome in family?
layer3.pvals <- list()
layer3.ests <- list()
layer3.ses <- list()
layer3.notes <- list()
for (i in 1:length(families)){
family <- families[i]
layer3.pvals[[family]] <- list()
layer3.ests[[family]] <- list()
layer3.ses[[family]] <- list()
layer3.notes[[family]] <- list()
outcomes <- get(family %.% '.outcomes')
for (j in 1:nrow(contrasts)){
contrast <- paste(contrasts[j, 'treat'],
contrasts[j, 'ctrl'],
sep = '.vs.'
)
layer3.pvals[[family]][[contrast]] <- numeric(0)
layer3.ests[[family]][[contrast]] <- numeric(0)
layer3.ses[[family]][[contrast]] <- numeric(0)
for (k in 1:length(outcomes)){
outcome <- outcomes[k]
layer3.pvals[[family]][[contrast]][outcome] <- NA_real_
layer3.ests[[family]][[contrast]][outcome] <- NA_real_
layer3.ses[[family]][[contrast]][outcome] <- NA_real_
layer3.notes[[family]][outcome] <- ''
}
}
}
### begin nested analyses ###
for (i in 1:length(families)){
family <- families[i]
family.outcomes <- get(family %.% '.outcomes')
family.controls <- get(family %.% '.controls')
family.controls.interactions <- as.character(
outer(treatments,
family.controls,
FUN = function(x, y) x %.% ':' %.% y
)
)
family.formula <-
'cbind(' %.% # outcomes
paste(family.outcomes,
collapse = ', '
) %.% ') ~\n0 +\n' %.%
paste(treatments, # treatments (base terms)
collapse = ' +\n'
) %.% ' +\n' %.%
paste(family.controls, # controls (base terms)
collapse = ' +\n'
)
cat(rep('=', 80),
'\n\nHYPOTHESIS FAMILY: ',
family,
'\n\nrunning mlm:\n\n',
family.formula,
'\n\n',
sep = ''
)
## run model
family.mod <- lm(family.formula, d)
## hack to eliminate NA coefs
if (any(is.na(coef(family.mod)))){
if ('mlm' %in% class(family.mod)){
drop <- rownames(coef(family.mod))[is.na(coef(family.mod))[, 1]]
} else {
drop <- names(coef(family.mod))[is.na(coef(family.mod))]
}
drop <- convert.interaction.names(drop,
c(family.controls,
family.controls.interactions
)
)
layer1.notes[[i]] <-
layer1.notes[[i]] %.%
'dropped the following coefs: ' %.%
paste(drop, sep = ', ') %.%
'\n\n'
family.formula <- gsub(
'\\s+\\+\\s+(' %.% paste(drop, collapse = '|') %.% ')',
'',
family.formula
)
family.mod <- lm(family.formula, d)
}
family.vcov <- vcovHC(family.mod)
if (is.null(dim(coef(family.mod)))){
coef.names <- names(coef(family.mod))
} else {
coef.names <- rownames(coef(family.mod))
}
### top layer: test overall significance of all contrasts on all outcomes ###
## convert interaction terms to whatever mlm() named it
treats <- convert.interaction.names(contrasts[, 'treat'], coef.names)
ctrls <- convert.interaction.names(contrasts[, 'ctrl'], coef.names)
## test jointly
lht.attempt <- tryCatch({
if ('mlm' %in% class(family.mod)){
contrast.lht <- linearHypothesis(
family.mod,
vcov. = family.vcov,
hypothesis.matrix = sprintf('%s - %s', treats, ctrls),
rhs = matrix(0, nrow = nrow(contrasts), ncol = length(family.outcomes)),
test = 'Pillai'
)
layer1.pvals[[i]] <- extract.lht(contrast.lht)[, 'Pr(>F)']
} else {
contrast.lht <- linearHypothesis(
family.mod,
vcov. = family.vcov,
hypothesis.matrix = sprintf('%s - %s', treats, ctrls),
rhs = matrix(0, nrow = nrow(contrasts), ncol = length(family.outcomes)),
test = 'F'
)
layer1.pvals[[i]] <- contrast.lht[['Pr(>F)']][2]
}
},
error = function(e){
warning(sprintf('caught error in %s family:', family), e)
## return error as string for inclusion in notes
'caught error: ' %.%
e %.%
'\n\n'
})
if (lht.attempt %like% 'caught error'){
layer1.notes[[i]] <-
layer1.notes[[i]] %.% lht.attempt
}
### layer 2: test each contrast individually on all outcomes ###
for (j in 1:nrow(contrasts)){
## test group equality on all outcomes
if ('mlm' %in% class(family.mod)){
contrast.lht <-
linearHypothesis(
family.mod,
vcov. = family.vcov,
hypothesis.matrix = sprintf('%s - %s', treats[j], ctrls[j]),
rhs = matrix(0, nrow = 1, ncol = length(family.outcomes)),
test = 'Pillai'
)
layer2.pvals[[i]][j] <- extract.lht(contrast.lht)[, 'Pr(>F)']
} else {
contrast.lht <- linearHypothesis(
family.mod,
vcov. = family.vcov,
hypothesis.matrix = sprintf('%s - %s', treats[j], ctrls[j]),
rhs = matrix(0, nrow = 1, ncol = length(family.outcomes)),
test = 'F'
)
layer2.pvals[[i]][j] <- contrast.lht[['Pr(>F)']][2]
}
}
### layer 3: test each contrast on each outcome individually ###
for (k in 1:length(family.outcomes)){
outcome <- family.outcomes[k]
outcome.formula <-
outcome %.% ' ~\n0 +\n' %.%
paste(treatments, # treatments (base terms)
collapse = ' +\n'
) %.% ' +\n' %.%
paste(family.controls, # controls (base terms)
collapse = ' +\n'
)
cat(rep('-', 40), '\n\nrunning lm:\n\n', outcome.formula, '\n\n', sep = '')
outcome.mod <- lm(outcome.formula, d)
## hack to eliminate NA coefs
if (any(is.na(coef(outcome.mod)))){
drop <- names(coef(outcome.mod))[is.na(coef(outcome.mod))]
drop <- convert.interaction.names(drop,
c(family.controls,
family.controls.interactions
)
)
layer3.notes[[i]][k] <-
layer3.notes[[i]][k] %.%
'dropped the following coefs: ' %.%
paste(drop, sep = ', ') %.%
'\n\n'
outcome.formula <- gsub(
'\\s+\\+\\s+(' %.% paste(drop, collapse = '|') %.% ')',
'',
outcome.formula
)
outcome.mod <- lm(outcome.formula, d)
}
outcome.vcov <- vcovHC(outcome.mod)
if (any(!is.finite(outcome.vcov))){
outcome.vcov <- vcov(outcome.mod)
layer3.notes[[i]][k] <-
layer3.notes[[i]][k] %.%
'falling back to non-robust vcov\n\n'
}
coef.names <- names(coef(outcome.mod))
for (j in 1:nrow(contrasts)){
## convert this interaction term to whatever lm() named it
treat <- convert.interaction.names(contrasts[j, 'treat'], coef.names)
ctrl <- convert.interaction.names(contrasts[j, 'ctrl'], coef.names)
## test group equality on this outcome
contrast.lht <- linearHypothesis(
outcome.mod,
vcov. = outcome.vcov,
hypothesis.matrix = sprintf('%s - %s', treat, ctrl),
test = 'F'
)
layer3.pvals[[i]][[j]][k] <- contrast.lht[['Pr(>F)']][2]
layer3.ests[[i]][[j]][k] <- (
coef(outcome.mod)[treat] - coef(outcome.mod)[ctrl]
) ## * attr(d[[outcome]], 'scaled:scale') # note: uncomment if rescaling
layer3.ses[[i]][[j]][k] <- sqrt(
outcome.vcov[treat, treat] +
outcome.vcov[ctrl, ctrl] -
2 * outcome.vcov[treat, ctrl]
)
## ## confirm
## linearHypothesis(
## outcome.mod,
## vcov. = outcome.vcov,
## hypothesis.matrix = sprintf('%s - %s', treat, ctrl),
## test = 'F'
## )
## (coef(outcome.mod)[treat] - coef(outcome.mod)[ctrl])^2 /
## (
## outcome.vcov[treat, treat] +
## outcome.vcov[ctrl, ctrl] -
## 2 * outcome.vcov[treat, ctrl]
## )
## linearHypothesis(
## outcome.mod,
## vcov. = outcome.vcov,
## hypothesis.matrix = sprintf('%s - %s', treat, ctrl),
## test = 'Chisq'
## )
## 2 - 2 * pnorm(abs(
## (coef(outcome.mod)[treat] - coef(outcome.mod)[ctrl]) /
## sqrt(
## outcome.vcov[treat, treat] +
## outcome.vcov[ctrl, ctrl] -
## 2 * outcome.vcov[treat, ctrl]
## )
## ))
}
}
}
#################################
## multiple testing correction ##
#################################
thresh <- .05
## if layer-1 f-test is infeasible for a family due to collinearity,
## obtain layer-1 p-values for that family by simes
for (i in which(is.na(layer1.pvals))){
layer1.pvals[i] <- simes(layer2.pvals[[i]])
}
## multiple testing adjustment for layer 1
layer1.pvals.adj <- p.adjust(layer1.pvals, 'BH')
layer1.nonnull.prop <- mean(layer1.pvals.adj < thresh)
## test layer-2 hypotheses only if layer 1 passes
layer2.pvals.adj <- layer2.pvals # start by copying unadjusted layer-2 p-values
layer2.nonnull.prop <- rep(NA, length(layer1.pvals.adj))
names(layer2.nonnull.prop) <- names(layer1.pvals.adj)
for (i in 1:length(layer1.pvals)){
if (layer1.pvals.adj[i] < thresh){ # if layer 1 passes
## adjust for multiplicity within layer 2...
layer2.pvals.adj[[i]] <- p.adjust(layer2.pvals[[i]], 'BH')
## ... and inflate to account for selection at layer 1
layer2.pvals.adj[[i]] <-
pmin(layer2.pvals.adj[[i]] / layer1.nonnull.prop, 1)
## keep track of selection at layer 2 for use in layer 3
layer2.nonnull.prop[i] <- mean(layer2.pvals.adj[[i]] < thresh)
} else { # if layer 1 fails
layer2.pvals.adj[[i]] <- rep(NA_real_, length(layer2.pvals[[i]]))
names(layer2.pvals.adj[[i]]) <- names(layer2.pvals[[i]])
}
}
## test layer-3 hypotheses only if layers 1 & 2 pass
layer3.pvals.adj <- layer3.pvals # start by copying unadjusted layer-3 p-values
for (i in 1:length(layer1.pvals.adj)){
for (j in 1:length(layer2.pvals.adj[[i]])){
##
if (layer1.pvals.adj[i] < thresh && # if layer 1 passes...
layer2.pvals.adj[[i]][j] < thresh # ... and if layer 2 passes
){
## adjust for multiplicity within layer 3...
layer3.pvals.adj[[i]][[j]] <- p.adjust(layer3.pvals[[i]][[j]], 'BH')
## ... and inflate to account for selection at layer 1
layer3.pvals.adj[[i]][[j]] <- pmin(
layer3.pvals.adj[[i]][[j]] / layer1.nonnull.prop / layer2.nonnull.prop[i],
1
)
} else {
layer3.pvals.adj[[i]][[j]] <- rep(NA_real_, length(layer3.pvals[[i]][[j]]))
names(layer3.pvals.adj[[i]][[j]]) <- names(layer3.pvals[[i]][[j]])
}
}
}
pvals.adj <- data.table(layer1 = character(0),
layer2 = character(0),
layer3 = character(0),
p.adj = numeric(0),
est = numeric(0),
se = numeric(0)
)
for (i in 1:length(layer1.pvals.adj)){
pvals.adj <- rbind(pvals.adj,
data.table(layer1 = names(layer1.pvals.adj)[i],
layer2 = 'overall',
layer3 = 'overall',
p.adj = layer1.pvals.adj[i],
est = NA_real_,
se = NA_real_
)
)
for (j in 1:length(layer2.pvals.adj[[i]])){
pvals.adj <- rbind(pvals.adj,
data.table(layer1 = names(layer1.pvals.adj)[i],
layer2 = names(layer2.pvals.adj[[i]])[j],
layer3 = 'overall',
p.adj = layer2.pvals.adj[[i]][j],
est = NA_real_,
se = NA_real_
)
)
for (k in 1:length(layer3.pvals.adj[[i]][[j]])){
pvals.adj <- rbind(pvals.adj,
data.table(layer1 = names(layer1.pvals.adj)[i],
layer2 = names(layer2.pvals.adj[[i]])[j],
layer3 = names(layer3.pvals.adj[[i]][[j]])[k],
p.adj = layer3.pvals.adj[[i]][[j]][k],
est = layer3.ests[[i]][[j]][k],
se = layer3.ses[[i]][[j]][k]
)
)
}
}
}
## write out
fwrite(pvals.adj, '../results/intermediate data/guncontrol_padj_basecontrol.csv')
## prettify for reading
pvals.adj.pretty <- pvals.adj
colnames(pvals.adj.pretty) <- gsub('layer1',
'layer1_hypothesisfamily',
colnames(pvals.adj.pretty)
)
colnames(pvals.adj.pretty) <- gsub('layer2',
'layer2_treatmentcontrast',
colnames(pvals.adj.pretty)
)
colnames(pvals.adj.pretty) <- gsub('layer3',
'layer3_specificoutcome',
colnames(pvals.adj.pretty)
)
pvals.adj.pretty[, layer2_treatmentcontrast := gsub(
'attitude\\.(pro|anti|neutral)(:seed\\.(pro|anti))?:recsys.(31|22)',
'\\1 \\3 \\4',
layer2_treatmentcontrast
)]
pvals.adj.pretty[, layer2_treatmentcontrast := gsub(
'.vs.',
' - ',
layer2_treatmentcontrast,
fixed = TRUE
)]
pvals.adj.pretty[, layer2_treatmentcontrast := gsub(
' +',
' ',
layer2_treatmentcontrast
)]
fwrite(pvals.adj.pretty,
'../results/intermediate data/gun control (issue 1)/guncontrol_padj_basecontrol_pretty.csv'
)
print('preregistered results:')
pvals.adj.pretty[p.adj < .05 & layer3_specificoutcome != 'overall',]
##############################################
## added 4 jun 2024 at request of reviewers ##
##############################################
## analyze components of main policy outcome index that relate to
## post-experiment w2 "understanding" of an issue, using w1 version
## of that same outcome as the only control (analogous to outcome index
## regression, which uses w2 index as outcome and w1 index as control)
## initialize results table
understanding.results <- data.table(layer2_treatmentcontrast = character(0),
layer3_specificoutcome = character(0),
est = numeric(0),
se = numeric(0),
p = numeric(0)
)
## loop over outcomes
for (k in 1:length(gunpolicy.outcomes.understanding)){
outcome <- gunpolicy.outcomes.understanding[k]
outcome.formula <-
outcome %.% ' ~\n0 +\n' %.%
paste(treatments, # treatments (base terms)
collapse = ' +\n'
) %.% ' +\n' %.%
paste(gsub('_w2', '', outcome), # controls (w1 outcome)
collapse = ' +\n'
)
cat(rep('-', 40), '\n\nrunning lm:\n\n', outcome.formula, '\n\n', sep = '')
outcome.mod <- lm(outcome.formula, d)
## hack to eliminate NA coefs
if (any(is.na(coef(outcome.mod)))){
drop <- names(coef(outcome.mod))[is.na(coef(outcome.mod))]
drop <- convert.interaction.names(drop,
c(family.controls,
family.controls.interactions
)
)
layer3.notes[[i]][k] <-
layer3.notes[[i]][k] %.%
'dropped the following coefs: ' %.%
paste(drop, sep = ', ') %.%
'\n\n'
outcome.formula <- gsub(
'\\s+\\+\\s+(' %.% paste(drop, collapse = '|') %.% ')',
'',
outcome.formula
)
outcome.mod <- lm(outcome.formula, d)
}
outcome.vcov <- vcovHC(outcome.mod)
if (any(!is.finite(outcome.vcov))){
outcome.vcov <- vcov(outcome.mod)
layer3.notes[[i]][k] <-
layer3.notes[[i]][k] %.%
'falling back to non-robust vcov\n\n'
}
coef.names <- names(coef(outcome.mod))
## loop over treatment contrasts
for (j in 1:nrow(contrasts)){
## convert this interaction term to whatever llm() named it
treat <- convert.interaction.names(contrasts[j, 'treat'], coef.names)
ctrl <- convert.interaction.names(contrasts[j, 'ctrl'], coef.names)
## test group equality on this outcome
contrast.lht <- linearHypothesis(
outcome.mod,
vcov. = outcome.vcov,
hypothesis.matrix = sprintf('%s - %s', treat, ctrl),
test = 'F'
)
## prettify name of contrast for readability
contrast <- treat %.% ' - ' %.% ctrl
contrast <- gsub('attitude\\.(pro|anti|neutral)', '\\1', contrast)
contrast <- gsub('seed\\.(pro|anti)', '\\1', contrast)
contrast <- gsub('recsys.(31|22)', '\\1', contrast)
contrast <- gsub(':', ' ', contrast)
contrast <- gsub(' +', ' ', contrast)
p <- contrast.lht[['Pr(>F)']][2]
est <- (
coef(outcome.mod)[treat] - coef(outcome.mod)[ctrl]
) ## * attr(d[[outcome]], 'scaled:scale') # note: uncomment if rescaling
se <- sqrt(
outcome.vcov[treat, treat] +
outcome.vcov[ctrl, ctrl] -
2 * outcome.vcov[treat, ctrl]
)
understanding.results <- rbind(
understanding.results,
data.table(
layer2_treatmentcontrast = contrast,
layer3_specificoutcome = outcome,
p,
est,
se
)
)
}
}
## conduct multiple testing adjustment within newly exploratory results
understanding.results[, p.adj := p.adjust(p, 'BH')]
print('exploratory results on understanding-related questions:')
understanding.results[p.adj < .05,]
fwrite(understanding.results,
'../results/intermediate data/gun control (issue 1)/guncontrol_understanding_basecontrol_pretty.csv'
)
#############################################################
## preregistered exploratory heterogeneous effect analysis ##
#############################################################
# outcome is gun_index_w2
# construct moderators by cutting demographics & pre-treatment vars at midpoint
d[,
pol_interest_hi := as.numeric(
pol_interest > median(pol_interest, na.rm = TRUE)
)]
d[,
age_hi := as.numeric(
age > median(age, na.rm = TRUE)
)]
d[,
freq_youtube_hi := as.numeric(
freq_youtube > median(freq_youtube, na.rm = TRUE)
)]
moderator_variables <- c('pol_interest_hi',
'age_hi',
'male',
'freq_youtube_hi'
)
## added 4 jun 2024 at request of reviewer
moderator_variables_revision <- 'college'
interaction_results <- data.table()
for (moderator_variable in c(moderator_variables, moderator_variables_revision)){
d[, moderator := get(moderator_variable)]
mod.attitude.anti <- lm(
gun_index_w2 ~
recsys.31 * moderator +
gun_index, # only control is pre-treatment outcome, as in primary analysis
data = d[attitude.anti == 1]
)
vcov.attitude.anti <- vcovHC(mod.attitude.anti)
test.attitude.anti <- coeftest(mod.attitude.anti, vcov.attitude.anti)
interaction_results <- rbind(
interaction_results,
data.table(subset = 'attitude.anti',
interaction = 'recsys.31:' %.% moderator_variable,
test.attitude.anti['recsys.31:moderator', , drop = FALSE]
),
fill = TRUE
)
mod.attitude.pro <- lm(
gun_index_w2 ~
recsys.31 * moderator +
gun_index, # only control is pre-treatment outcome, as in primary analysis
data = d[attitude.pro == 1]
)
vcov.attitude.pro <- vcovHC(mod.attitude.pro)
test.attitude.pro <- coeftest(mod.attitude.pro, vcov.attitude.pro)
interaction_results <- rbind(
interaction_results,
data.table(subset = 'attitude.pro',
interaction = 'recsys.31:' %.% moderator_variable,
test.attitude.pro['recsys.31:moderator', , drop = FALSE]
),
fill = TRUE
)
mod.attitude.neutral.seed.anti <- lm(
gun_index_w2 ~
recsys.31 * moderator +
gun_index, # only control is pre-treatment outcome, as in primary analysis
data = d[attitude.neutral == 1 & seed.anti == 1]
)
vcov.attitude.neutral.seed.anti <- vcovHC(mod.attitude.neutral.seed.anti)
test.attitude.neutral.seed.anti <- coeftest(mod.attitude.neutral.seed.anti,
vcov.attitude.neutral.seed.anti
)
interaction_results <- rbind(
interaction_results,
data.table(subset = 'attitude.neutral.seed.anti',
interaction = 'recsys.31:' %.% moderator_variable,
test.attitude.neutral.seed.anti[
'recsys.31:moderator', , drop = FALSE
]
),
fill = TRUE
)
mod.attitude.neutral.seed.pro <- lm(
gun_index_w2 ~
recsys.31 * moderator +
gun_index, # only control is pre-treatment outcome, as in primary analysis
data = d[attitude.neutral == 1 & seed.pro == 1]
)
vcov.attitude.neutral.seed.pro <- vcovHC(mod.attitude.neutral.seed.pro)
test.attitude.neutral.seed.pro <- coeftest(mod.attitude.neutral.seed.pro,
vcov.attitude.neutral.seed.pro )
interaction_results <- rbind(
interaction_results,
data.table(subset = 'attitude.neutral.seed.pro',
interaction = 'recsys.31:' %.% moderator_variable,
test.attitude.neutral.seed.pro[
'recsys.31:moderator', , drop = FALSE
]
),
fill = TRUE
)
}
# no significant heterogeneity even before multiple testing correction
print('heterogeneity results before multiple correction:')
interaction_results[`Pr(>|t|)` < .05,]
# none survives a BH correction
interaction_results[, p.adj := p.adjust(`Pr(>|t|)`, 'BH')]
print('heterogeneity p-values after multiple correction:')
interaction_results[, p.adj]
## updated 4 jun 2024 at request of reviewer
colnames(interaction_results) <- c(
subset = 'subset',
interaction = 'interaction',
Estimate = 'est',
`Std. Error` = 'se',
`t value` = 't',
`Pr(>|t|)` = 'p',
p.adj = 'p.adj'
)[colnames(interaction_results)]
fwrite(interaction_results,
'../results/intermediate data/gun control (issue 1)/guncontrol_heterogeneity_basecontrol.csv'
)
###############################################
## added 30 sep 2024 at request of reviewers ##
###############################################
## what are minimum detectable effects, given multiple testing correction?
n_sims <- 1000
params_sims <- expand.grid(seed = 19104 + 0:(n_sims - 1),
effect = seq(from = .01, to = .05, by = .001)
)
## step 1: identify largest p-value s.t. we would have rejected layer-1 null
## (that at least one treatment contrast has effect on policy index)
## to do this, we hold fixed p-values for all other layer-1 hypothesis families
layer1.pvals.mde <- layer1.pvals
layer1.pvals.mde['gunpolicy'] <- 0
while (p.adjust(layer1.pvals.mde, 'BH')['gunpolicy'] <= .05){
layer1.pvals.mde['gunpolicy'] <- layer1.pvals.mde['gunpolicy'] + .001
}
pval.cutoff <- layer1.pvals.mde['gunpolicy']
print('to achieve significance of policy attitude family at layer 1 (pooled test of any effect on policy index from any contrast) when correcting for multiple layer-1 hypothesis families, this is the minimum cutoff value after conducting simes correction of layer 2 pvals:')
pval.cutoff
## if layer-1 null was rejected for the policy outcome, then we would use this
## correction factor when interpreting layer-2 p-values (for specific contrasts)
layer1.nonnull.prop.if.gt.cutoff <- mean(c(
p.adjust(layer1.pvals.mde, 'BH')[c('platform', 'media', 'affpol')] < .05,
TRUE
))
## the sims below will only examine 3/1 vs 2/2 treatment contrasts, so we will
## hold fixed the layer-2 p-values that relate to seed contrasts
pvals.for.seed.contrasts.on.policyindex <- layer2.pvals$mwpolicy[
c('attitude.neutral:seed.pro:recsys.31.vs.attitude.neutral:seed.anti:recsys.31',
'attitude.neutral:seed.pro:recsys.22.vs.attitude.neutral:seed.anti:recsys.22'
)
]
## step 2: prepare simulations based on real data ------------------------------
mod.attitude.anti <- lm(
gun_index_w2 ~ recsys.31 + gun_index,
data = d[attitude.anti == 1]
)
X.attitude.anti <- model.matrix(mod.attitude.anti)
residual.sd.attitude.anti <- sd(resid(mod.attitude.anti))
## confirm that this recovers fitted values
## model.matrix(mod.attitude.anti) %*% coef(mod.attitude.anti)
assert_that(all(
predict(mod.attitude.anti) ==
X.attitude.anti %*% coef(mod.attitude.anti)
))
## we will create simulated outcomes, given hypothesized treatment effect
## == intercept + <-- part A
## real coef * real pretreatment attitude + <-- part A
## hypothesized treatment effect * real treatment status + <-- part B
## rnorm(mean = 0, sd = real residual outcome sd) <-- part C
## A: generate fitted values under hypothesized effect size
coef.attitude.anti.baseline <- coef(mod.attitude.anti)
coef.attitude.anti.baseline['recsys.31'] <- 0
Y.attitude.anti.baseline <-
as.numeric(X.attitude.anti %*% coef.attitude.anti.baseline)
## C: will be added below with hypothesized effect * treatment
## B: will be drawn below with rnorm(mean=0, sd=residual_sd)
## repeat above for respondents with pro attitude
mod.attitude.pro <- lm(
gun_index_w2 ~ recsys.31 + gun_index,
data = d[attitude.pro == 1]
)
X.attitude.pro <- model.matrix(mod.attitude.pro)
residual.sd.attitude.pro <- sd(resid(mod.attitude.pro))
coef.attitude.pro.baseline <- coef(mod.attitude.pro)
coef.attitude.pro.baseline['recsys.31'] <- 0
Y.attitude.pro.baseline <-
as.numeric(X.attitude.pro %*% coef.attitude.pro.baseline)
## repeat above for respondents with neutral attitude assigned to pro seed
mod.attitude.neutral.seed.pro <- lm(
gun_index_w2 ~ recsys.31 + gun_index,
data = d[attitude.neutral == 1 & seed.pro == 1]
)
X.attitude.neutral.seed.pro <- model.matrix(mod.attitude.neutral.seed.pro)
residual.sd.attitude.neutral.seed.pro <- sd(resid(mod.attitude.neutral.seed.pro))
coef.attitude.neutral.seed.pro.baseline <- coef(mod.attitude.neutral.seed.pro)
coef.attitude.neutral.seed.pro.baseline['recsys.31'] <- 0
Y.attitude.neutral.seed.pro.baseline <-
as.numeric(X.attitude.neutral.seed.pro %*% coef.attitude.neutral.seed.pro.baseline)
## repeat above for respondents with neutral attitude assigned to anti seed
mod.attitude.neutral.seed.anti <- lm(
gun_index_w2 ~ recsys.31 + gun_index,
data = d[attitude.neutral == 1 & seed.anti == 1]
)
X.attitude.neutral.seed.anti <- model.matrix(mod.attitude.neutral.seed.anti)
residual.sd.attitude.neutral.seed.anti <- sd(resid(mod.attitude.neutral.seed.anti))
coef.attitude.neutral.seed.anti.baseline <- coef(mod.attitude.neutral.seed.anti)
coef.attitude.neutral.seed.anti.baseline['recsys.31'] <- 0
Y.attitude.neutral.seed.anti.baseline <-
as.numeric(X.attitude.neutral.seed.anti %*% coef.attitude.neutral.seed.anti.baseline)
## step 3: conduct sims --------------------------------------------------------
sims.attitude.anti <- foreach(seed = params_sims$seed,
effect = params_sims$effect,
.combine = rbind
) %dopar%
{
set.seed(seed)
Y <-
Y.attitude.anti.baseline +
effect * X.attitude.anti[, 'recsys.31'] +
rnorm(
n = nrow(X.attitude.anti),
mean = 0,
sd = residual.sd.attitude.anti
)
mod <- lm(Y ~ 0 + X.attitude.anti)
smry <- coeftest(mod, vcovHC(mod))
cbind(
seed,
effect,
data.table(smry['X.attitude.antirecsys.31', , drop = FALSE])
)
}
sims.attitude.pro <- foreach(seed = params_sims$seed,
effect = params_sims$effect,
.combine = rbind
) %dopar%
{
set.seed(seed)
Y <-
Y.attitude.pro.baseline +
effect * X.attitude.pro[, 'recsys.31'] +
rnorm(
n = nrow(X.attitude.pro),
mean = 0,
sd = residual.sd.attitude.pro
)
mod <- lm(Y ~ 0 + X.attitude.pro)
smry <- coeftest(mod, vcovHC(mod))
cbind(
seed,
effect,
data.table(smry['X.attitude.prorecsys.31', , drop = FALSE])
)
}
sims.attitude.neutral.seed.anti <- foreach(seed = params_sims$seed,
effect = params_sims$effect,
.combine = rbind
) %dopar%
{
set.seed(seed)
Y <-
Y.attitude.neutral.seed.anti.baseline +
effect * X.attitude.neutral.seed.anti[, 'recsys.31'] +
rnorm(
n = nrow(X.attitude.neutral.seed.anti),
mean = 0,
sd = residual.sd.attitude.neutral.seed.anti
)
mod <- lm(Y ~ 0 + X.attitude.neutral.seed.anti)
smry <- coeftest(mod, vcovHC(mod))
cbind(
seed,
effect,
data.table(smry['X.attitude.neutral.seed.antirecsys.31', , drop = FALSE])
)
}
sims.attitude.neutral.seed.pro <- foreach(seed = params_sims$seed,
effect = params_sims$effect,
.combine = rbind
) %dopar%
{
set.seed(seed)
Y <-
Y.attitude.neutral.seed.pro.baseline +
effect * X.attitude.neutral.seed.pro[, 'recsys.31'] +
rnorm(
n = nrow(X.attitude.neutral.seed.pro),
mean = 0,
sd = residual.sd.attitude.neutral.seed.pro
)
mod <- lm(Y ~ 0 + X.attitude.neutral.seed.pro)
smry <- coeftest(mod, vcovHC(mod))
cbind(
seed,
effect,
data.table(smry['X.attitude.neutral.seed.prorecsys.31', , drop = FALSE])
)
}
## step 4: analyze power results -----------------------------------------------
## without multiple-testing corrections
print('mde for respondents with anti attitude (conventional analysis w/o correction):')
sims.attitude.anti[,
.(p.reject = mean(`Pr(>|t|)` < .05)),
by = effect
][p.reject >= .8, min(effect)]
print('mde for respondents with pro attitude (conventional analysis w/o correction):')
sims.attitude.pro[,
.(p.reject = mean(`Pr(>|t|)` < .05)),
by = effect
][p.reject >= .8, min(effect)]
print('mde for respondents with neutral attitude assigned to pro seed (conventional analysis w/o correction):')
sims.attitude.neutral.seed.anti[,
.(p.reject = mean(`Pr(>|t|)` < .05)),
by = effect
][p.reject >= .8, min(effect)]
print('mde for respondents with neutral attitude assigned to anti seed (conventional analysis w/o correction):')
sims.attitude.neutral.seed.pro[,
.(p.reject = mean(`Pr(>|t|)` < .05)),
by = effect
][p.reject >= .8, min(effect)]
## with multiple testing correction
sims <- rbind(
sims.attitude.anti,
sims.attitude.pro,
sims.attitude.neutral.seed.anti,
sims.attitude.neutral.seed.pro
)
sims.layer1 <- sims[
,
.(pval.pooled = ifelse(
## if these results would lead us to reject layer-1 pooled null of no effect
## on policy attitudes from any treatment contrast
simes(c(
`Pr(>|t|)`,
pvals.for.seed.contrasts.on.policyindex
)) <= pval.cutoff,
## disaggregate layer-2 results report with procedure from above
## (BH correction, then inflate by 1/prop of layer-1 sig results)
## then subset to only those p-values relating to 3/1 vs 2/2 contrast
## to see if any are <.05 after full correction procedure
yes = min(
p.adjust(c(`Pr(>|t|)`, pvals.for.seed.contrasts.on.policyindex),
'BH'
)[1:4] / layer1.nonnull.prop.if.gt.cutoff
),
no = Inf
)
),
by = .(seed, effect)
]
print('with multiple testing correction:')
sims.layer1[, .(p.reject = mean(pval.pooled <= pval.cutoff)), by = effect]
print('mde:')
sims.layer1[,
.(p.reject = mean(pval.pooled <= pval.cutoff)),
by = effect
][p.reject >= .8, min(effect)]