library(dplyr)
t.test(height ~ gender, data=starwars, alternative="less")
Welch Two Sample t-test
data: height by gender
t = -1.5596, df = 37.315, p-value = 0.06365
alternative hypothesis: true difference in means between group feminine and group masculine is less than 0
95 percent confidence interval:
-Inf 0.9641724
sample estimates:
mean in group feminine mean in group masculine
164.6875 176.5161 Weibliche Charaktere sind nicht signifikant kleiner als männliche (\(t=-1.56\), \(p = .064\)).
t.test(mass ~ gender, data=starwars, alternative="less")
Welch Two Sample t-test
data: mass by gender
t = -1.936, df = 49.094, p-value = 0.02932
alternative hypothesis: true difference in means between group feminine and group masculine is less than 0
95 percent confidence interval:
-Inf -6.897942
sample estimates:
mean in group feminine mean in group masculine
54.68889 106.14694 Weibliche Charaktere sind signifikant leichter als männliche (\(t=-1.94\), \(p = .029\)).
library(palmerpenguins)
with(
subset(penguins, species == "Adelie" | species == "Chinstrap"),
t.test(bill_length_mm ~ species)
)
Welch Two Sample t-test
data: bill_length_mm by species
t = -21.865, df = 106.97, p-value < 2.2e-16
alternative hypothesis: true difference in means between group Adelie and group Chinstrap is not equal to 0
95 percent confidence interval:
-10.952948 -9.131917
sample estimates:
mean in group Adelie mean in group Chinstrap
38.79139 48.83382 with(
subset(penguins, species == "Adelie" | species == "Gentoo"),
t.test(bill_length_mm ~ species)
)
Welch Two Sample t-test
data: bill_length_mm by species
t = -24.725, df = 242.58, p-value < 2.2e-16
alternative hypothesis: true difference in means between group Adelie and group Gentoo is not equal to 0
95 percent confidence interval:
-9.407672 -8.019303
sample estimates:
mean in group Adelie mean in group Gentoo
38.79139 47.50488 with(
subset(penguins, species == "Gentoo" | species == "Chinstrap"),
t.test(bill_length_mm ~ species)
)
Welch Two Sample t-test
data: bill_length_mm by species
t = 2.706, df = 129.22, p-value = 0.00773
alternative hypothesis: true difference in means between group Chinstrap and group Gentoo is not equal to 0
95 percent confidence interval:
0.3572698 2.3006212
sample estimates:
mean in group Chinstrap mean in group Gentoo
48.83382 47.50488 with(
subset(penguins, species == "Adelie" | species == "Chinstrap"),
t.test(bill_depth_mm ~ species)
)
Welch Two Sample t-test
data: bill_depth_mm by species
t = -0.43771, df = 137.75, p-value = 0.6623
alternative hypothesis: true difference in means between group Adelie and group Chinstrap is not equal to 0
95 percent confidence interval:
-0.4095657 0.2611044
sample estimates:
mean in group Adelie mean in group Chinstrap
18.34636 18.42059 with(
subset(penguins, species == "Adelie" | species == "Gentoo"),
t.test(bill_depth_mm ~ species)
)
Welch Two Sample t-test
data: bill_depth_mm by species
t = 25.337, df = 271.98, p-value < 2.2e-16
alternative hypothesis: true difference in means between group Adelie and group Gentoo is not equal to 0
95 percent confidence interval:
3.102837 3.625651
sample estimates:
mean in group Adelie mean in group Gentoo
18.34636 14.98211 with(
subset(penguins, species == "Gentoo" | species == "Chinstrap"),
t.test(bill_depth_mm ~ species)
)
Welch Two Sample t-test
data: bill_depth_mm by species
t = 21.01, df = 122.3, p-value < 2.2e-16
alternative hypothesis: true difference in means between group Chinstrap and group Gentoo is not equal to 0
95 percent confidence interval:
3.114497 3.762452
sample estimates:
mean in group Chinstrap mean in group Gentoo
18.42059 14.98211 pairwise.t.test(penguins$bill_length_mm, penguins$species)
Pairwise comparisons using t tests with pooled SD
data: penguins$bill_length_mm and penguins$species
Adelie Chinstrap
Chinstrap <2e-16 -
Gentoo <2e-16 0.0032
P value adjustment method: holm pairwise.t.test(penguins$bill_depth_mm, penguins$species)
Pairwise comparisons using t tests with pooled SD
data: penguins$bill_depth_mm and penguins$species
Adelie Chinstrap
Chinstrap 0.65 -
Gentoo <2e-16 <2e-16
P value adjustment method: holm t.test(extra ~ group, data=sleep, paired=TRUE)
Paired t-test
data: extra by group
t = -4.0621, df = 9, p-value = 0.002833
alternative hypothesis: true mean difference is not equal to 0
95 percent confidence interval:
-2.4598858 -0.7001142
sample estimates:
mean difference
-1.58 Die mittlere Differenz beträgt −1.58, das 95%-Konfidenzintervall erstreckt sich von −2.46 bis −0.7.