---
title: 'Linguistic Data: Quantitative Analysis and Visualisation'
author: "Ilya Schurov, Olga Lyashevskaya, George Moroz, Alla Tambovtseva"
date: "09 February 2018"
output:
  html_document:
    df_print: paged
  html_notebook: default
  pdf_document: default
subtitle: 'ANOVA: analysis of variance'
---

Load data on Icelandic:

```{r}
phono <- read.csv("http://math-info.hse.ru/f/2018-19/ling-data/icelandic.csv")
```

Look at groups of consonants:

```{r}
table(phono$cons1)
```

Create a boxplot for vowel duration for each group of consonants:

```{r}
boxplot(phono$vowel.dur ~ phono$cons1) 
```

Perform ANOVA:

```{r}
res <- aov(phono$vowel.dur ~ phono$cons1)
res
```

More informative summary:

```{r}
# H0: there are no difference in population means by groups
summary(res)
```

**Question:** judging by the output above, can we conclude that average vowel duration differ significantly in different groups of consonants?