From ac9299b9db62f3347e7bfb872f3f85424991f396 Mon Sep 17 00:00:00 2001 From: Daniel Enrique Date: Sun, 8 Mar 2020 03:47:44 -0400 Subject: [PATCH 1/2] Changed conf interval of mean code --- exercise2.R | 68 +++++++++++++++++++++++++++++++++++++++++++++-------- 1 file changed, 58 insertions(+), 10 deletions(-) diff --git a/exercise2.R b/exercise2.R index ff5bb85..691aef2 100644 --- a/exercise2.R +++ b/exercise2.R @@ -1,5 +1,5 @@ get_measures = function(x) { - return(c(mean(x), getmode(x), median(x), var(x), sd(x), sd(x) / mean(x))) + return(c(Mean = mean(x), Mode = getmode(x), Median = median(x), Variance = var(x), Sd = sd(x), DC = sd(x) / mean(x))) } getmode <- function(v) { @@ -52,16 +52,30 @@ cols = length(graphic_names) M = t(matrix(measures, ncol=cols, byrow=TRUE)) +par(mfrow=c(2,3)) + for(i in c(1:cols)) barplot(M[i,], names.arg=bar_names, main=graphic_names[i], col="#a1e6e3") mean_conf_interval = function(sample, alpha) { - m = 0 - s = 1 + m = mean(sample) + s = sd(sample) n = length(sample) - error = qnorm(1 - alpha) * s / sqrt(n) - return(c("start" = m - error, "end" = m + error)) + error = 0 + + if(n > 30) { + error = qnorm(1 - alpha / 2) + } + + else { + error = qt(1 - alpha / 2, n - 1) + } + + st = m - error * s / sqrt(n) + nd = m + error * s / sqrt(n) + + return(c(start=st, end=nd)) } variance_conf_interval = function(sample, alpha) { @@ -71,14 +85,48 @@ variance_conf_interval = function(sample, alpha) { q1 = qchisq(1 - alpha / 2, n - 1) q2 = qchisq(alpha / 2, n - 1) - start <- (n - 1) * vr / q1 - end <- (n - 1) * vr / q2 + st = (n - 1) * vr / q1 + nd = (n - 1) * vr / q2 - return(c("start" = start, "end" = end)) + return(c(start=st, end=nd)) } +print("Mean confidence intervals for S20 and S20R") print(mean_conf_interval(sample_20, 0.05)) -print(mean_conf_interval(sample_30, 0.05)) +print(mean_conf_interval(sample_20_r, 0.05)) +print("", quote=FALSE) +print("Var confidence interval for S20 and S20R") print(variance_conf_interval(sample_20, 0.05)) -print(variance_conf_interval(sample_30, 0.05)) \ No newline at end of file +print(variance_conf_interval(sample_20_r, 0.05)) +print("", quote=FALSE) + +print("Mean confidence intervals for S30 and S30R") +print(mean_conf_interval(sample_30, 0.05)) +print(mean_conf_interval(sample_30_r, 0.05)) +print("", quote=FALSE) + +print("Var confidence interval for S30 and S30R") +print(variance_conf_interval(sample_30, 0.05)) +print(variance_conf_interval(sample_30_r, 0.05)) +print("", quote=FALSE) + +print("Mean confidence intervals for S150 and S150R") +print(mean_conf_interval(sample_150, 0.05)) +print(mean_conf_interval(sample_150_r, 0.05)) +print("", quote=FALSE) + +print("Var confidence interval for S150 and S150R") +print(variance_conf_interval(sample_150, 0.05)) +print(variance_conf_interval(sample_150_r, 0.05)) +print("", quote=FALSE) + +print("Mean confidence intervals for S350 and S350R") +print(mean_conf_interval(sample_350, 0.05)) +print(mean_conf_interval(sample_350_r, 0.05)) +print("", quote=FALSE) + +print("Var confidence interval for S350 and S350R") +print(variance_conf_interval(sample_350, 0.05)) +print(variance_conf_interval(sample_350_r, 0.05)) +print("", quote=FALSE) \ No newline at end of file From b3c19296dbe5c34b43ef2a7c18e61055b419469d Mon Sep 17 00:00:00 2001 From: Daniel Enrique Date: Sun, 8 Mar 2020 04:49:21 -0400 Subject: [PATCH 2/2] Exported graphics to png --- exercise2.R | 3 +++ 1 file changed, 3 insertions(+) diff --git a/exercise2.R b/exercise2.R index 691aef2..3617a7b 100644 --- a/exercise2.R +++ b/exercise2.R @@ -52,11 +52,14 @@ cols = length(graphic_names) M = t(matrix(measures, ncol=cols, byrow=TRUE)) +png("sample_analysis.png", width=800, height=800) par(mfrow=c(2,3)) for(i in c(1:cols)) barplot(M[i,], names.arg=bar_names, main=graphic_names[i], col="#a1e6e3") +dev.off() + mean_conf_interval = function(sample, alpha) { m = mean(sample) s = sd(sample)