Tips for effective data visualization 💅

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layout: true
  
<div class="my-footer">
<span>
<a href="https://DataScience4Psych.github.io/DataScience4Psych/" target="_blank">Data Science for Psychologists</a>
</span>
</div>

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# Designing effective visualizations

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## Keep it simple

.pull-left-narrow[
<img src="img/pie-3d.jpg" width="100%" style="display: block; margin: auto;" />
]
.pull-right-wide[
<img src="d13_goodviz_files/figure-html/pie-to-bar-1.png" width="100%" style="display: block; margin: auto;" />
]

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## Use	color	to	draw	attention

<br>

.pull-left[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-2-1.png" width="100%" style="display: block; margin: auto;" />
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-3-1.png" width="100%" style="display: block; margin: auto;" />
]

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## Tell a story

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# Wrapping Up...

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# Principles for effective visualizations

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## Principles	for	effective	visualizations

- Order matters
- Put long categories on the y-axis
- Keep	scales consistent
- Select meaningful colors
- Use meaningful and nonredundant labels

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## Data

In September 2019, YouGov survey asked 1,639 GB adults the following question:

.pull-left[
> In hindsight, do you think Britain was right/wrong to vote to leave EU?
>
>- Right to leave  
>- Wrong to leave  
>- Don't know

]
.pull-right[

<img src="d13_goodviz_files/figure-html/unnamed-chunk-6-1.png" width="100%" style="display: block; margin: auto;" />
]

.footnote[ 
Source: [YouGov Survey Results](https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/x0msmggx08/YouGov%20-%20Brexit%20and%202019%20election.pdf), retrieved Oct 7, 2019
]

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# Order matters

---

## Alphabetical order is rarely ideal

.medi.pull-left[

``` r
ggplot(brexit, aes(x = opinion)) +
  geom_bar()
```
]
.pull-right-wide[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-7-1.png" width="85%" style="display: block; margin: auto;" />
]
---

## Order by frequency

`fct_infreq`: Reorder factors' levels by frequency

``` r
ggplot(brexit, aes(x = fct_infreq(opinion))) +
  geom_bar()
```

<img src="d13_goodviz_files/figure-html/unnamed-chunk-8-1.png" width="60%" style="display: block; margin: auto;" />
]

---

## Clean up labels
.medi.pull-left[

``` r
ggplot(brexit, aes(x = opinion)) +
  geom_bar() +
* labs(
*   x = "Opinion",
*   y = "Count"
* )
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-9-1.png" width="100%" style="display: block; margin: auto;" />
]
---

## Alphabetical order is rarely ideal

.midi.pull-left-narrow[

``` r
ggplot(brexit, aes(x = region)) +
  geom_bar()
```
]

.pull-right-wide[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-10-1.png" width="100%" style="display: block; margin: auto;" />
]

---

## Use inherent level order

`fct_relevel`: Reorder factor levels using a custom order

``` r
brexit <- brexit %>%
  mutate(
*   region = fct_relevel(
      region,
      "london", "rest_of_south", "midlands_wales", "north", "scot"
    )
  )
```

---
.pull-left-wide[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-12-1.png" width="120%" style="display: block; margin: auto;" />
]
---
## Clean up labels

`fct_recode`: Change factor levels by hand

``` r
brexit <- brexit %>%
  mutate(
*   region = fct_recode(
      region,
      London = "london",
      `Rest of South` = "rest_of_south",
      `Midlands / Wales` = "midlands_wales",
      North = "north",
      Scotland = "scot"
    )
  )
```

---

## Clean!

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# Put long categories on the y-axis

---

## Long categories can be hard to read

---

## Move them to the y-axis
.medi[

``` r
ggplot(brexit, aes(x = region)) +
  geom_bar() +
* coord_flip()
```

<img src="d13_goodviz_files/figure-html/unnamed-chunk-16-1.png" width="55%" style="display: block; margin: auto;" />
]
---

## Move them to the y-axis
.medi[

``` r
*ggplot(brexit, aes(y = region)) +
  geom_bar()
```

<img src="d13_goodviz_files/figure-html/unnamed-chunk-17-1.png" width="55%" style="display: block; margin: auto;" />
]

---

## And reverse the order of levels
`fct_rev`: Reverse order of factor levels

.medi.pull-left[

``` r
*ggplot(brexit, aes(y = fct_rev(region))) +
  geom_bar()
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-18-1.png" width="100%" style="display: block; margin: auto;" />
]

---

## Clean up labels

.medi.pull-left[

``` r
ggplot(brexit, aes(y = fct_rev(region))) +
  geom_bar() +
* labs(
*   x = "Count",
*   y = "Region"
* )
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-19-1.png" width="100%" style="display: block; margin: auto;" />
]

---

# Pick a purpose

---

## Segmented bar plots can be hard to read

.medi.pull-left-wide[

``` r
*ggplot(brexit, aes(y = region, fill = opinion)) +
  geom_bar()
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-20-1.png" width="100%" style="display: block; margin: auto;" />
]

---

---

## Use facets

.medi.pull-left-wide[

``` r
ggplot(brexit, aes(y = opinion, fill = region)) +
  geom_bar() +
* facet_wrap(~region, nrow = 1)
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-22-1.png" width="100%" style="display: block; margin: auto;" />
]
---

---

## Avoid redundancy?

.medi.pull-left[

``` r
ggplot(brexit, aes(y = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1)
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-24-1.png" width="100%" style="display: block; margin: auto;" />
]
---

---

## Redundancy can help tell a story

.medi.pull-left[

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1)
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-26-1.png" width="100%" style="display: block; margin: auto;" />
]
---

---

## Be selective with redundancy

.medi.pull-left[

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1) +
* guides(fill = FALSE)
```

]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-28-1.png" width="100%" style="display: block; margin: auto;" />
]
---

---

## Informative labels

.medi.pull-left[

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1) +
  guides(fill = FALSE) +
  labs(
*   title = "Was Britain right/wrong to vote to leave EU?",
    x = NULL, y = NULL
  )
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-30-1.png" width="100%" style="display: block; margin: auto;" />
]

---

---

## A bit more info

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1) +
  guides(fill = FALSE) +
  labs(
    title = "Was Britain right/wrong to vote to leave EU?",
*   subtitle = "YouGov Survey Results, 2-3 September 2019",
*   caption = "Source: https://d25d2506sfb94s.cloudfront.net/cumulus_uploads/document/x0msmggx08/YouGov%20-%20Brexit%20and%202019%20election.pdf",
    x = NULL, y = NULL
  )
```
]

---

---

## Let's do better

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1) +
  guides(fill = FALSE) +
  labs(
    title = "Was Britain right/wrong to vote to leave EU?",
    subtitle = "YouGov Survey Results, 2-3 September 2019",
*   caption = "Source: bit.ly/2lCJZVg",
    x = NULL, y = NULL
  )
```

]

---

---

## Fix up facet labels

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region,
    nrow = 1,
*   labeller = label_wrap_gen(width = 12)
  ) + 
  guides(fill = FALSE) +
  labs(
    title = "Was Britain right/wrong to vote to leave EU?",
    subtitle = "YouGov Survey Results, 2-3 September 2019",
    caption = "Source: bit.ly/2lCJZVg",
    x = NULL, y = NULL
  )
```
]

---

---
class: middle

# Select meaningful colors

---

## Rainbow colors are not always the right choice

.medi.pull-left[

``` r
ggplot(brexit, aes(y= region, fill = opinion)) +
  geom_bar(position = "fill") 
```
]

]

---

---

## Manually choose colors when needed

.midi.pull-left-wide[

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1, labeller = label_wrap_gen(width = 12)) +
  guides(fill = FALSE) +
  labs(title = "Was Britain right/wrong to vote to leave EU?",
       subtitle = "YouGov Survey Results, 2-3 September 2019",
       caption = "Source: bit.ly/2lCJZVg",
       x = NULL, y = NULL) +
* scale_fill_manual(values = c(
*   "Wrong" = "red",
*   "Right" = "green",
*   "Don't know" = "gray"
* ))
```
]

]

---
.center[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-38-1.png" width="80%" style="display: block; margin: auto;" />
]

---

## Choosing better colors

.center.large[
[colorbrewer2.org](https://colorbrewer2.org/)
]

---

## Use better colors
.midi.pull-left-wide[

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1, labeller = label_wrap_gen(width = 12)) +
  guides(fill = FALSE) +
  labs(title = "Was Britain right/wrong to vote to leave EU?",
       subtitle = "YouGov Survey Results, 2-3 September 2019",
       caption = "Source: bit.ly/2lCJZVg",
       x = NULL, y = NULL) +
  scale_fill_manual(values = c(
*   "Wrong" = "#ef8a62",
*   "Right" = "#67a9cf",
*   "Don't know" = "gray"
  ))
```
]

]

---

.center[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-41-1.png" width="80%" style="display: block; margin: auto;" />
]

---

## Select theme

``` r
ggplot(brexit, aes(y = opinion, fill = opinion)) +
  geom_bar() +
  facet_wrap(~region, nrow = 1, labeller = label_wrap_gen(width = 12)) +
  guides(fill = FALSE) +
  labs(title = "Was Britain right/wrong to vote to leave EU?",
       subtitle = "YouGov Survey Results, 2-3 September 2019",
       caption = "Source: bit.ly/2lCJZVg",
       x = NULL, y = NULL) +
  scale_fill_manual(values = c("Wrong" = "#ef8a62",
                               "Right" = "#67a9cf",
                               "Don't know" = "gray")) +
* theme_minimal()
```

---

.center[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-42-1.png" width="80%" style="display: block; margin: auto;" />
]

---

## Spot the Difference

.pull-right-narrow[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-43-1.png" width="60%" style="display: block; margin: auto;" />
]

.pull-left-narrow[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-44-1.png" width="60%" style="display: block; margin: auto;" />
]

---

.your-turn[
### .hand[Your turn!]
.midi[
- `AE 07 - Brexit + Telling stories with dataviz` > `brexit.Rmd`. 
- Change the visualization in three different ways to tell slightly different stories with it each time.
]
]

---

## Viridis scale works well with ordinal data 
.medi.pull-left-wide[

``` r
ggplot(brexit, aes(y = region, fill = opinion)) +
  geom_bar(position = "fill") +
  scale_fill_viridis_d()
```
]
.pull-right[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-45-1.png" width="100%" style="display: block; margin: auto;" />
]

---
.center[
<img src="d13_goodviz_files/figure-html/unnamed-chunk-46-1.png" width="80%" style="display: block; margin: auto;" />
]

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### Clean up labels (Again)

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# Sources

- Mine Çetinkaya-Rundel's Data Science in a Box ([link](https://datasciencebox.org/))

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# Wrapping Up...