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# List of packages
packages <- c("tidyverse", "infer", "fst", "modelsummary", "effects", "survey", "MASS", "aod", "interactions", "kableExtra", "flextable", "scales") # add any you need here

# Install packages if they aren't installed already
new_packages <- packages[!(packages %in% installed.packages()[,"Package"])]
if(length(new_packages)) install.packages(new_packages)

# Load the packages
lapply(packages, library, character.only = TRUE)
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Task 1

Use data for Germany and the variable coding for model3 and model4 from the tutorial (i.e., both for the cleaning & recode, as well as the linear model formulas). Do a modelsummary table displaying both model outputs. Interpret the coefficients for the MLR without the interaction (i.e., the first displayed model), and interpret model fit metrics for both models.

germany_data <- read_fst("germany_data.fst")
dg <- germany_data
dg$weight <- dg$dweight * dg$pweight
survey_design <- svydesign(ids = ~1, data = dg, weights = ~weight)
dg <- dg %>%
  mutate(behave = ipbhprp,
         secure = impsafe,
         safety = ipstrgv,
         tradition = imptrad,
         rules = ipfrule) %>%
  mutate(across(c("behave", "secure", "safety", "tradition", "rules"),
                ~ na_if(.x, 7) %>% na_if(8) %>% na_if(9))) %>%
  # Apply the reverse coding
  mutate(across(c("behave", "secure", "safety", "tradition", "rules"), ~ 7 - .x ))

# Now you can calculate 'schwartzauth' after the NA recoding
dg$auth <- scales::rescale(dg$behave + 
                      dg$secure + 
                      dg$safety + 
                      dg$tradition + 
                      dg$rules, to=c(0,100), na.rm=TRUE)


dg <- dg %>% filter(!is.na(auth))
dg <- dg %>%
  mutate(
    polID = case_when(
      lrscale %in% 0:3 ~ "Left",                    
      lrscale %in% 7:10 ~ "Right",                     
      lrscale %in% 4:6 ~ "Moderate",                  
      lrscale %in% c(77, 88, 99) ~ NA_character_      
    ),
   religious = case_when(
      rlgdgr %in% c(77, 88, 99) ~ NA_real_,
      TRUE ~ rlgdgr
    )
  )
dg <- dg %>% filter(!is.na(polID))
dg <- dg %>% filter(!is.na(religious))
model3 <- lm(auth ~ polID + religious, data = dg, weights = weight)
model4 <- lm(auth ~ polID + religious + polID*religious, data = dg, weights = weight)
modelsummary(
  list(model3, model4),
  fmt = 1,
  estimate  = c( "{estimate} ({std.error}){stars}",
                "{estimate} ({std.error}){stars}"),
  statistic = NULL)
 (1)   (2)
(Intercept) 55.3 (0.3)*** 56.4 (0.3)***
polIDModerate 4.6 (0.3)*** 3.4 (0.4)***
polIDRight 7.7 (0.4)*** 4.2 (0.7)***
religious 0.9 (0.0)*** 0.6 (0.1)***
polIDModerate × religious 0.3 (0.1)***
polIDRight × religious 0.8 (0.1)***
Num.Obs. 23373 23373
R2 0.048 0.050
R2 Adj. 0.048 0.050
AIC 200594.1 200558.6
BIC 200634.4 200615.0
Log.Lik. −100292.049 −100272.298
RMSE 17.27 17.24

For both models, model fit metrics do not differ much. However , interaction coeffiients are statistically significant p < 0.001.

The adjusted R-Squared of 0.048 means that after accounting for the number of predictors (religiousness and political ideology), these variables explain 4.8% of the variance in the authoritarian values scale for Germany. (for model 3)

For Model 4 0.050 R-squared means that after accounting for the number of predictors (religiousness and political ideology), these variables explain 5% of the variance in the authoritarian values scale for Germany. (considering their interaction)

Task 2

Now generate the model4 interaction plot that we did in the tutorial, but again using the German data instead of the French. Interpret.

interaction_plot <- effect("polID*religious", model4, na.rm=TRUE)

plot(interaction_plot,
     main="Interaction effect",
     xlab="Religiousness",
     ylab="Authoritarian attitudes scale")

interaction_plot
## 
##  polID*religious effect
##           religious
## polID             0        2        5        8       10
##   Left     56.40706 57.56775 59.30879 61.04983 62.21053
##   Moderate 59.85063 61.66176 64.37844 67.09513 68.90626
##   Right    60.60237 63.35032 67.47224 71.59416 74.34211

Answer: There are no slopes that are discernibly unparralel, which means there are no large interaction effects

Task 3

Use data for the Netherlands and the variable coding for model5 and model6 from the tutorial (i.e., both for the cleaning & recode, as well as the linear model formulas). Do a modelsummary table displaying both model outputs. Interpret the coefficients for the MLR without the interaction (i.e., the first displayed model), and interpret model fit metrics for both models.

netherlands_data <- read_fst("netherlands_data.fst")
dn <- netherlands_data
dn$weight <- dn$dweight * dn$pweight
survey_design <- svydesign(ids = ~1, data = dn, weights = ~weight)
dn <- dn %>%
  mutate(behave = ipbhprp,
         secure = impsafe,
         safety = ipstrgv,
         tradition = imptrad,
         rules = ipfrule) %>%
  mutate(across(c("behave", "secure", "safety", "tradition", "rules"),
                ~ na_if(.x, 7) %>% na_if(8) %>% na_if(9))) %>%
  # Apply the reverse coding
  mutate(across(c("behave", "secure", "safety", "tradition", "rules"), ~ 7 - .x ))

# Now you can calculate 'schwartzauth' after the NA recoding
dn$auth2 <- scales::rescale(dn$behave + 
                      dn$secure + 
                      dn$safety + 
                      dn$tradition + 
                      dn$rules, to=c(0,100), na.rm=TRUE)


dn <- dn %>% filter(!is.na(auth2))
dn <- dn %>%
  mutate(
    cohort = ifelse(yrbrn < 1930 | yrbrn > 2000, NA, yrbrn),
    # Recoding generational cohorts based on the year of birth (yrbrn).
    # The year of birth is categorized into different generational cohorts.
    # Interwar (1900-1945), Baby Boomers (1946-1964), Gen X (1965-1979), Millennials (1980-1996).
    # The 'TRUE' line is a catch-all that keeps the original year of birth for those not in these ranges.
    gen = case_when(
      yrbrn %in% 1900:1945 ~ "1",
      yrbrn %in% 1946:1964 ~ "2",
      yrbrn %in% 1965:1979 ~ "3",
      yrbrn %in% 1980:1996 ~ "4",
      TRUE ~ as.character(yrbrn)  
    ),
    # After recoding, the gen variable is converted into a factor with labels for clearer interpretation.
    # Factors are used in R to handle categorical variables.
    gen = factor(gen,
                 levels = c("1", "2", "3", "4"),
                 labels = c("Interwar", "Baby Boomers", "Gen X", "Millennials"))
  )
table(dn$gen)
## 
##     Interwar Baby Boomers        Gen X  Millennials 
##         3771         6147         4548         2730
dn <- dn %>%
  mutate(religion = case_when(
    rlgblg == 2 ~ "No",
    rlgblg == 1 ~ "Yes",
    rlgblg %in% c(7, 8, 9) ~ NA_character_,
    TRUE ~ as.character(rlgblg)
  ))

# check
table(dn$religion)
## 
##    No   Yes 
## 10913  6750
dn <- dn %>%
  mutate(ID = case_when(
    lrscale >= 0 & lrscale <= 4 ~ "Left",
    lrscale >= 6 & lrscale <= 10 ~ "Right",
    lrscale > 10 ~ NA_character_,  # Set values above 10 as NA
    TRUE ~ NA_character_  # Ensure value 5 and any other unexpected values are set as NA
  ))
table(dn$ID)
## 
##  Left Right 
##  5449  7010
model5 <- lm(auth2 ~ religion + ID + gen, data = dn, weights = weight)
model6 <- lm(auth2 ~ religion + ID + gen + religion*gen, data = dn, weights = weight)
modelsummary(
  list(model5, model6),
  fmt = 1,
  estimate  = c( "{estimate} ({std.error}){stars}",
                "{estimate} ({std.error}){stars}"),
  statistic = NULL,
  coef_omit = "Intercept")
 (1)   (2)
religionYes 7.2 (0.3)*** 5.7 (0.7)***
IDRight 4.2 (0.3)*** 4.3 (0.3)***
genBaby Boomers −5.2 (0.4)*** −5.9 (0.6)***
genGen X −7.7 (0.4)*** −8.8 (0.6)***
genMillennials −8.4 (0.5)*** −9.7 (0.6)***
religionYes × genBaby Boomers 1.1 (0.8)
religionYes × genGen X 2.3 (0.9)**
religionYes × genMillennials 2.9 (1.0)**
Num.Obs. 12116 12116
R2 0.124 0.125
R2 Adj. 0.124 0.125
AIC 101219.3 101213.5
BIC 101271.2 101287.5
Log.Lik. −50602.672 −50596.757
RMSE 15.27 15.26

Answer:

-genGen X (-7.7): This means that Holding everything else constant, on average genX are 7.7 units less on the authoritarian values scale, compared to interwar for Netherlands

-genMillennials (-8.4): This means that Holding everything else constant, on average millennials are 8.4 units less on the authortarian values scale, compared to interwar for Netherlands

For both models, model fit metrics do not differ much.

The adjusted R-Squared of 0.124 means that after accounting for the number of predictors (religion, political ideology (LR) and generation), these variables explain 12.4% of the variance in the authoritarian values scale for Netherlands. (for model 5)

For Model 6 0.125 R-squared means that after accounting for the number of predictors (religion, political ideology (LR) and generation), these variables explain 12.5% of the variance in the authoritarian values scale for Germany. (considering their interaction)

All coefficients including interaction coefficients seem to be statistically significant p < 0.05 except the interaction coefficient between having a religion and baby boomers (religionYes × genBaby Boomers)

Task 4

Produce the model7 interaction plot from the tutorial, but again using the Netherlands data. Interpret.

dn <- dn %>%
  mutate(
    polID2 = case_when(
      lrscale %in% 0:3 ~ "Left",                    
      lrscale %in% 7:10 ~ "Right",                     
      lrscale %in% 4:6 ~ "Moderate",                  
      lrscale %in% c(77, 88, 99) ~ NA_character_      
    )
  )
dn <- dn %>% filter(!is.na(polID2))
model7 <- lm(auth2 ~ + cohort + polID2 + cohort*polID2, data = dn, weights = weight)
interact_plot(model7, pred = cohort, modx = polID2, jnplot = TRUE)

Answer: since the slopes are not parallel there is an interaction effect between cohort and political ideology (left, moderate, right) in predicting authoritarian scale scores for the netherlands.

Task 5

Produce the model8 interaction plot from the tutorial, but again using the Netherlands data. Interpret.

dn <- dn %>%
  mutate(
   religious2 = case_when(
      rlgdgr %in% c(77, 88, 99) ~ NA_real_,
      TRUE ~ rlgdgr
    )
  )
model8 <- lm(auth2 ~ religious2 + ID + religious2*ID, data = dn, weights = weight)
interact_plot(model8, pred = religious2, modx = ID, jnplot = TRUE)

Answer: Since the slopes are rather parallel and do not intersect with each other, there seems to be no interaction effects between how religious you are and your political ideology (left or right) in determining authoritarian scale scores for the Netherlands.

End