Li Liu_Josselyn_Homework_3
Li Liu_Josselyn
2024-03-06
# List of packages
packages <- c("tidyverse", "infer", "fst") # 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)## ── Attaching core tidyverse packages ──────────────────────── tidyverse 2.0.0 ──
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## ✔ ggplot2 3.4.4 ✔ tibble 3.2.1
## ✔ lubridate 1.9.3 ✔ tidyr 1.3.0
## ✔ purrr 1.0.2
## ── Conflicts ────────────────────────────────────────── tidyverse_conflicts() ──
## ✖ dplyr::filter() masks stats::filter()
## ✖ dplyr::lag() masks stats::lag()
## ℹ Use the conflicted package (<http://conflicted.r-lib.org/>) to force all conflicts to become errors## Warning: package 'infer' was built under R version 4.3.3## [[1]]
## [1] "lubridate" "forcats" "stringr" "dplyr" "purrr" "readr"
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## [13] "graphics" "grDevices" "utils" "datasets" "methods" "base"
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## [1] "fst" "infer" "lubridate" "forcats" "stringr" "dplyr"
## [7] "purrr" "readr" "tidyr" "tibble" "ggplot2" "tidyverse"
## [13] "stats" "graphics" "grDevices" "utils" "datasets" "methods"
## [19] "base"ess <- read_fst("All-ESS-Data.fst")france_data <- read.fst("france_data.fst")Task 1
Based on the recoding of lrscale for “left” and “right” and omitting “moderates” (see Tutorial 4), and educ.ba from this tutorial, do the long form coding for Chi-Square. Using the steps outlined in the tutorial, first generate the tables of expected proportions and frequencies. Determine and interpret the critical value for independence. Finally, determine and interpret both the Pearson’s chi-squared statistic and the p-value. Discuss main takeaways.
france_data <- ess %>%
filter(cntry == "FR") %>%
mutate(
ID = case_when(
lrscale %in% 0:3 ~ "Left",
lrscale %in% 7:10 ~ "Right",
lrscale %in% c(77, 88, 99) ~ NA_character_
),
# Recoding education with case_when for consistency
educ.ba = case_when(
essround < 5 & edulvla == 5 ~ "BA or more",
essround >= 5 & edulvlb > 600 ~ "BA or more",
TRUE ~ "No BA"
)
) %>%
# Ensure all NAs are handled uniformly
mutate(
edulvla = ifelse(edulvla %in% c(77, 88), NA_integer_, edulvla),
edulvlb = ifelse(edulvlb %in% c(5555, 7777, 8888), NA_integer_, edulvlb),
educ.ba = as.character(educ.ba)
)tab_dat <- france_data
# Create a crosstable and save it into the object mytab
mytab <- table(tab_dat$ID, tab_dat$educ.ba)
# Calculate row-wise sums of counts in table
rsums <- rowSums(mytab)
# Calculate column-wise sums of counts in table
csums <- colSums(mytab)
# Get the total count of the table (N)
N <- sum(mytab)
# Generate table of expected proportions
ptab <- tcrossprod(rsums/N, csums/N)
cat("Table of Expected Proportions:\n")## Table of Expected Proportions:print(ptab)## [,1] [,2]
## [1,] 0.1311243 0.3914592
## [2,] 0.1197912 0.3576253# Table of expected frequencies
ftab <- N * ptab
cat("Table of Expected Frequencies:\n")## Table of Expected Frequencies:print(ftab)## [,1] [,2]
## [1,] 1181.561 3527.439
## [2,] 1079.439 3222.561# Critical Value for Independence:
alpha <- 0.05
c_val <- qchisq(alpha, df = 1, lower.tail = FALSE)
cat("Critical Value:", round(c_val, 3), "\n")## Critical Value: 3.841# Pearson's chi-squared statistic:
test_stat <- sum((mytab - ftab)^2 / ftab)
cat("Pearson's X^2:", round(test_stat, 4), "\n")## Pearson's X^2: 100.8551There is a statistically significant association between placement on left right scale and one’s educational level. The probability of placement on left right scale is not the same across different education levels.
# p-value:
p_val <- pchisq(test_stat, df = 1, lower.tail = F)
cat("p-value:", round(p_val, 4), "\n")## p-value: 0# Using chisq.test for validation:
cat("Chi-squared test result:\n")## Chi-squared test result:print(chisq.test(mytab, correct = F))##
## Pearson's Chi-squared test
##
## data: mytab
## X-squared = 100.86, df = 1, p-value < 2.2e-16p-value < 2.2e-16: This is another representation of the p-value in scientific notation because it’s extremely close to 0.
The extremely small p-value means that we reject the null hypothesis, the two variables are independent of each other.
Task 2
Do Steps 1 to 3 using the infer package (as we did in the tutorial), for the variables sbbsntx (recoded to the corresponding 5 categories) as the response and domicil (recoded to urban and rural, setting 2 to urban instead of peri-urban) as the explanatory variable for the country of France.
See variable info here: https://ess.sikt.no/en/datafile/ffc43f48-e15a-4a1c-8813-47eda377c355/92?tab=1&elements=[%22874a86e2-a0f6-40b4-aef7-51c8eed98a7d/1%22])
Provide interpretations of the output (consider the variable info).
france_data <- ess %>%
filter(cntry == "FR") %>%
mutate(
sbbsntx = case_when(
sbbsntx == 1 ~ "Agree strongly",
sbbsntx == 2 ~ "Agree",
sbbsntx == 3 ~ "Neither agree nor disagree",
sbbsntx == 4 ~ "Disagree",
sbbsntx == 5 ~ "Disagree strongly",
TRUE ~ NA_character_
),
domicil = case_when(
domicil == "1" ~ "Urban",
domicil == "2" ~ "Urban",
domicil == "3" ~ "Rural",
domicil == "4" ~ "Rural",
domicil == "5" ~ "Rural",
TRUE ~ NA_character_
)
)
france_data <- france_data %>%
filter(!is.na(sbbsntx), !is.na(domicil))Step 1: Calculate the test statistic of your sample
test_stat <- france_data %>%
specify(explanatory = domicil,
response = sbbsntx) %>%
hypothesize(null = "independence") %>%
calculate(stat = "Chisq")
print(test_stat$stat)## X-squared
## 19.97187A chisq-statistic of 19.97 is quite large, indicating a significant difference in social benefits services between those living in urban and rural area. It suggests that the mean social benefits services is different for the two geographic area groups.
Step 2: Simulate the null distribution
null_distribution <- france_data %>%
specify(explanatory = domicil,
response = sbbsntx) %>%
hypothesize(null = "independence") %>%
generate(reps = 1000, type = "permute") %>%
calculate(stat = "Chisq")Step 3: Calculate the p-value of your sample
p_val <- null_distribution %>%
get_pvalue(obs_stat = test_stat, direction = "greater") ## Warning: Please be cautious in reporting a p-value of 0. This result is an approximation
## based on the number of `reps` chosen in the `generate()` step.
## ℹ See `get_p_value()` (`?infer::get_p_value()`) for more information.p_val## # A tibble: 1 × 1
## p_value
## <dbl>
## 1 0There is strong evidence to reject the null.
Task 3
Now do Step 4 (i.e., the null distribution visualization with confidence intervals) for the same variables and country as Task 2, and interpret the output.
Step 4: Visualize
conf_int <- null_distribution %>%
get_confidence_interval(level = 0.95, type = "percentile")
null_distribution %>%
visualize() +
shade_p_value(obs_stat = test_stat, direction = "two-sided") +
shade_confidence_interval(endpoints = conf_int)## Warning: Chi-Square usually corresponds to right-tailed tests. Proceed with
## caution.
null_distribution## Response: sbbsntx (factor)
## Explanatory: domicil (factor)
## Null Hypothesis: independence
## # A tibble: 1,000 × 2
## replicate stat
## <int> <dbl>
## 1 1 3.15
## 2 2 6.15
## 3 3 2.20
## 4 4 5.58
## 5 5 2.62
## 6 6 0.868
## 7 7 3.35
## 8 8 8.60
## 9 9 8.84
## 10 10 8.76
## # ℹ 990 more rowsBased on this visualization, there is a significant difference or association in social benefits services between those living in urban and rural area. The data provides strong evidence to reject the null hypothesis of independence between the explanatory and response variables in the context of the analysis conducted.
Task 4
Conduct Steps 1 to 3 using the infer package (as we did in the tutorial), for the variables ccrdprs (leaving it on the 0-10 numeric scale) as the response (or outcome) variable and lrscale (recoded as left and right, omitting “moderates” as we did in Task 1) as the explanatory variable.
Variable info here: https://ess.sikt.no/en/datafile/ffc43f48-e15a-4a1c-8813-47eda377c355/92?tab=1&elements=[%2283b08cf2-508e-49a0-9fc8-c3cc281290ec/4%22]
Provide interpretations of the output (consider the variable info).
france_data <- ess %>%
filter(cntry == "FR") %>%
mutate(
ccrdprs = case_when(
ccrdprs == 0 ~ "Not at all",
ccrdprs == 1 ~ "1",
ccrdprs == 2 ~ "2",
ccrdprs == 3 ~ "3",
ccrdprs == 4 ~ "4",
ccrdprs == 5 ~ "5",
ccrdprs == 6 ~ "6",
ccrdprs == 7 ~ "7",
ccrdprs == 8 ~ "8",
ccrdprs == 9 ~ "9",
ccrdprs == 10 ~ "A great deal",
TRUE ~ NA_character_
),
lrscale = case_when(
lrscale %in% 0:3 ~ "Left",
lrscale %in% 7:10 ~ "Right",
lrscale %in% c(77, 88, 99) ~ NA_character_
)
) %>%
filter(!is.na(ccrdprs), !is.na(lrscale))Step 1: Calculate the test statistic of your sample
test_stat <- france_data %>%
specify(explanatory = lrscale,
response = ccrdprs) %>%
hypothesize(null = "independence") %>%
calculate(stat = "Chisq")
print(test_stat$stat)## X-squared
## 35.04425A chisq-statistic of 35.04 is quite large, indicating a significant difference in personal responsibility to reduce climate change between those placement on left and right It suggests that the mean in personal responsibility to reduce climate change is different for the two political placement groups.
Step 2: Simulate the null distribution
null_distribution <- france_data %>%
specify(explanatory = lrscale,
response = ccrdprs) %>%
hypothesize(null = "independence") %>%
generate(reps = 1000, type = "permute") %>%
calculate(stat = "Chisq")Step 3: Calculate the p-value of your sample
p_val <- null_distribution %>%
get_pvalue(obs_stat = test_stat, direction = "two-sided") ## Warning: Please be cautious in reporting a p-value of 0. This result is an approximation
## based on the number of `reps` chosen in the `generate()` step.
## ℹ See `get_p_value()` (`?infer::get_p_value()`) for more information.p_val## # A tibble: 1 × 1
## p_value
## <dbl>
## 1 0There is strong evidence to reject the null.
Task 5
Now do Step 4 (i.e., the null distribution visualization with confidence intervals) for the same variables and country as Task 4, and interpret the output.
Step 4: Visualize
conf_int <- null_distribution %>%
get_confidence_interval(level = 0.95, type = "percentile")
null_distribution %>%
visualize() +
shade_p_value(obs_stat = test_stat, direction = "two-sided") +
shade_confidence_interval(endpoints = conf_int)## Warning: Chi-Square usually corresponds to right-tailed tests. Proceed with
## caution.
null_distribution## Response: ccrdprs (factor)
## Explanatory: lrscale (factor)
## Null Hypothesis: independence
## # A tibble: 1,000 × 2
## replicate stat
## <int> <dbl>
## 1 1 11.9
## 2 2 6.23
## 3 3 6.85
## 4 4 9.14
## 5 5 21.3
## 6 6 9.42
## 7 7 5.70
## 8 8 20.6
## 9 9 2.78
## 10 10 10.8
## # ℹ 990 more rowsBased on this visualization, there is a significant association between the political placement and the personal responsibility to reduce climate change, rejecting the null hypothesis of independence. The exact p-value, which is likely very small based on this graph, quantifies the strength of evidence against the null hypothesis.