Lab 5

Assignment link

1.1 and 1.2

95% CI formula again: \(mean \pm 1.96\frac{standard\ deviation}{number\ of\ observation}\)

library(tidyverse)
icelandic <- read.csv("https://goo.gl/7gIjvK")
icelandic %>% 
  group_by(aspiration, speaker) %>%
  summarise(mean = mean(vowel.dur),
            CI = 1.96*sd(vowel.dur)/sqrt(length(vowel.dur)))

## Source: local data frame [10 x 4]
## Groups: aspiration [?]
## 
##    aspiration speaker      mean       CI
##        <fctr>  <fctr>     <dbl>    <dbl>
## 1          no   brs02  95.27593 4.396906
## 2          no   bte03 102.75791 6.399292
## 3          no    jj04  95.72652 5.542966
## 4          no   shg05  77.65635 4.242477
## 5          no    tt01 100.59767 5.625930
## 6         yes   brs02  72.87988 4.009082
## 7         yes   bte03  95.40109 4.503628
## 8         yes    jj04  86.80463 4.634397
## 9         yes   shg05  63.27287 3.363331
## 10        yes    tt01  78.25853 3.498920

1.3

icelandic %>% 
  group_by(aspiration, speaker) %>%
  summarise(mean = mean(vowel.dur),
            CI = 1.96*sd(vowel.dur)/sqrt(length(vowel.dur))) %>% 
    ggplot(aes(aspiration, mean))+
  geom_point()+
  geom_errorbar(aes(ymin= mean-CI,
                    ymax = mean+CI), width = 0.3)+
  facet_wrap(~speaker)+
  labs(title = "Mean vowel duration with 95% confidence interval",
       caption = "Data from (Coretta 2017)")

1.4

icelandic %>% 
  ggplot(aes(vowel.dur, fill = aspiration, color = aspiration))+
  geom_density(alpha = 0.4)+
  geom_rug()+
  facet_wrap(~speaker)+
  labs(title = "Vowel duration density plot",
       caption = "Data from (Coretta 2017)",
       x = "vowel duration")

icelandic %>% 
  ggplot(aes(sample = vowel.dur, color = aspiration))+
  geom_qq()+
  facet_wrap(~speaker, scales = "free")+
  labs(title = "Vowel duration density plot",
       caption = "Data from (Coretta 2017)")

1.6-1.10

table(icelandic$speaker)

## 
## brs02 bte03  jj04 shg05  tt01 
##   163   157   151   160   175

icelandic_1 <- subset(icelandic,speaker == "brs02")
icelandic_2 <- subset(icelandic,speaker == "bte03")
icelandic_3 <- subset(icelandic,speaker == "jj04")
icelandic_4 <- subset(icelandic,speaker == "shg05")
icelandic_5 <- subset(icelandic,speaker == "tt01")
t.test.results_1 <- t.test(vowel.dur~aspiration, icelandic_1)
t.test.results_2 <- t.test(vowel.dur~aspiration, icelandic_2)
t.test.results_3 <- t.test(vowel.dur~aspiration, icelandic_3)
t.test.results_4 <- t.test(vowel.dur~aspiration, icelandic_4)
t.test.results_5 <- t.test(vowel.dur~aspiration, icelandic_5)

1.11-1.15

library(lsr)
cohensD(vowel.dur~aspiration, data = icelandic_1)

## [1] 1.15919

cohensD(vowel.dur~aspiration, data = icelandic_2)

## [1] 0.2908475

cohensD(vowel.dur~aspiration, data = icelandic_3)

## [1] 0.3902875

cohensD(vowel.dur~aspiration, data = icelandic_4)

## [1] 0.8318769

cohensD(vowel.dur~aspiration, data = icelandic_5)

## [1] 1.001688