Time

# Time

**Session 13**

]

---

# Plan for today

.box-5.medium.sp-after[Axis issues]

.box-3.medium.sp-after[Visualizing time]

.box-1.medium[Starting, ending, and decomposing time]

---

layout: false
name: axis-issues
class: center middle section-title section-title-5 animated fadeIn

# Axis issues

---

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# Is truncating the y-axis misleading?

---

# Don't be too extreme!

.box-inv-5.medium[It is actually more legal to truncate the y-axis than you might think!]

---

# When is it okay to truncate?

.pull-left[
<figure>
 <img src="img/13/us_gdp_us_gdp_chartbuilder-3.png" alt="GDP not truncated, from Quartz" title="GDP not truncated, from Quartz" width="100%">
</figure>
]

.pull-right[
<figure>
 <img src="img/13/us_gdp_us_gdp_chartbuilder-2.png" alt="GDP truncated, from Quartz" title="GDP truncated, from Quartz" width="100%">
</figure>
]

???

Stock prices too

https://qz.com/418083/its-ok-not-to-start-your-y-axis-at-zero/

---

# When is it okay to truncate?

.pull-left.center[
<figure>
 <img src="img/13/uber-sign.jpg" alt="Sign in an Uber car about rating system" title="Sign in an Uber car about rating system" width="60%">
</figure>
]

.pull-right[
<figure>
 <img src="img/13/uber-scale.jpg" alt="Internal rating system at Uber" title="Internal rating system at Uber" width="100%">
</figure>
]

???

https://www.buzzfeed.com/carolineodonovan/the-fault-in-five-stars

http://www.businessinsider.com/leaked-charts-show-how-ubers-driver-rating-system-works-2015-2

---

# When is it okay to truncate?

.pull-left[
<figure>
 <img src="img/13/oral_temperature_sara_bob_chartbuilder.png" alt="Temperature not truncated, from Quartz" title="Temperature not truncated, from Quartz" width="100%">
</figure>
]

.pull-right[
<figure>
 <img src="img/13/oral_temperature_sara_bob_chartbuilder-1.png" alt="Temperature truncated, from Quartz" title="Temperature truncated, from Quartz" width="100%">
</figure>
]

???

https://qz.com/418083/its-ok-not-to-start-your-y-axis-at-zero/

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# Never on bar charts

.pull-left.center[

]

.pull-right.center[

]

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# Zero is okay too!

.box-inv-5.medium[Just because you don't *have to* start at 0 doesn't mean you should *never* start at 0]

.box-5.small.sp-after[It's often a good idea!]

---

# Keep axis scales consistent

.center[
<figure>
 <img src="img/13/fox-co-covid-cases.jpg" alt="FOX Colorado affiliate graph with COVID-19 cases" title="FOX Colorado affiliate graph with COVID-19 cases" width="55%">
 <figcaption>FOX affiliate in Colorado reporting on COVID-19 cases</figcaption>
</figure>
]

???

http://freerangestats.info/blog/2020/04/06/crazy-fox-y-axis

---

# Keep axis scales consistent

&nbsp;

.center[
<figure>
 <img src="img/13/08fig21.jpg" alt="Good and bad treatment of missing values in x-axis" title="Good and bad treatment of missing values in x-axis" width="80%">
</figure>
]

???

Alberto Cairo, *The Truthful Art*, chapter 8, figure 8.21

---

# Don’t impute across categories

.pull-left[
<img src="13-slides_files/figure-html/likert-imputation-bad-1.png" width="100%" style="display: block; margin: auto;" />
]

.pull-right[
<img src="13-slides_files/figure-html/likert-good-1.png" width="100%" style="display: block; margin: auto;" />
]

---

layout: false
name: visualizing-time
class: center middle section-title section-title-3 animated fadeIn

# Visualizing time

---

---

# Showing changes over time

.box-inv-3.sp-after[Can use all sorts of `geom` s: lines, columns, points, heatmaps, densities, maps, etc.]

.box-3.medium[→ & ↓]

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# Time on x-axis + `geom_line/col()`

.pull-left[
<img src="13-slides_files/figure-html/covid-unemp-claims-1.png" width="100%" style="display: block; margin: auto;" />
]

.pull-right.center[
<figure>
 <img src="img/13/nyt_2020-05-09.jpg" alt="Front page of the NYT, May 9, 2020" title="Front page of the NYT, May 9, 2020" width="50%">
 <figcaption><a href="https://static01.nyt.com/images/2020/05/09/nytfrontpage/scan.pdf" target="_blank">Front page of the New York Times</a>, May 9, 2020</figcaption>
</figure>
]

???

Monthly change in jobs since end of WWII

The New York Times front page, May 9, 2020

https://www.nytimes.com/issue/todayspaper/2020/05/09/todays-new-york-times

https://static01.nyt.com/images/2020/05/09/nytfrontpage/scan.pdf

---

# Time on x-axis + `geom_tile()`

.center[
<figure>
 <img src="img/13/08fig28.jpg" alt="Heat map by Jorge Camões" title="Heat map by Jorge Camões" title="Heat map by Jorge Camões" title="Heat map by Jorge Camões" width="65%">
 <figcaption>Figure 8.28 in Alberto Cairo's The Truthful Art: Heat map by Jorge Camões</figcaption>
</figure>
]

???

Alberto Cairo, *The Truthful Art*, chapter 8, figure 8.28

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# Time on y-axis + `geom_density()`

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# Time in animation + `geom_point()`

.center[
<figure>
 <img src="img/03/rosling-tedx.jpg" alt="Hans Rosling" title="Hans Rosling" width="65%">
</figure>
]

???

Source: [New York Times](https://www.nytimes.com/2017/02/09/world/europe/hans-rosling-dead-statistician.html)

---

# Time in maps

.center[
<figure>
 <img src="img/13/08fig30.jpg" alt="Map by Jorge Camões" title="Map by Jorge Camões" width="50%">
 <figcaption>Figure 8.30 in Alberto Cairo's The Truthful Art: Map of the spread of Walmart by Jorge Camões</figcaption>
</figure>
]

???

Alberto Cairo, *The Truthful Art*, chapter 8, figure 8.30

---

# Time in `geom_col()` + small multiples

.center[
<figure>
 <img src="img/13/us-cities-kitchen-counter-cropped.png" alt="ZZZ" title="ZZZ" width="100%">
 <figcaption>Kieran Healy, <a href="https://kieranhealy.org/blog/archives/2020/05/21/the-kitchen-counter-observatory/" target="_blank">“The Kitchen Counter Observatory”</a></figcaption>
</figure>
]

???

https://kieranhealy.org/blog/archives/2020/05/21/the-kitchen-counter-observatory/

---

# Don't go wild with time mapping!

.center[
<figure>
 <img src="img/13/covid-conversation-spiral.png" alt="Change in COVID death rates" title="Change in COVID death rates" width="65%">
 <figcaption><a href="https://theconversation.com/three-graphs-that-show-a-global-slowdown-in-covid-19-deaths-135756" target="_blank">Tornado plot</a>: When a curve crosses the left of the central axis, the number of deaths per day falls</figcaption>
</figure>
]

???

https://theconversation.com/three-graphs-that-show-a-global-slowdown-in-covid-19-deaths-135756

---

# Interpreting tornado plots

???

http://www.bewitched.com/demo/tornado/tornado.html

http://www.dannydorling.org/books/SLOWDOWN/Illustrations.html

---

# Better with multiple plots

.pull-left[
<img src="13-slides_files/figure-html/unemp-inflation-path-1.png" width="100%" style="display: block; margin: auto;" />
]

.pull-right[
<img src="13-slides_files/figure-html/unemp-inflation-good-1.png" width="100%" style="display: block; margin: auto;" />

]

---

layout: false
name: decomposing
class: center middle section-title section-title-1 animated fadeIn

# Starting, ending, and decomposing time

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# ∞

.box-inv-1.medium[You always have to choose a start and end point]

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# Measles vaccine was pretty effective!

???

Data sources listed here:

https://commons.m.wikimedia.org/wiki/File:Measles_US_1938-2019.png

I used [this big PDF table from the CDC](https://web.archive.org/web/20190120205018/https://www.cdc.gov/vaccines/pubs/pinkbook/downloads/appendices/e/reported-cases.pdf), used some random online PDF → CSV converter, and cleaned up the data by hand in Excel:

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# Measles vaccine was *incredible*!

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# Seasonality

]

]

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# Decomposition

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# Birthday decomposition

.center[
<figure>
 <img src="img/13/bda_cover.png" alt="Bayesian Data Analysis cover" title="Bayesian Data Analysis cover" width="45%">
 <figcaption>Cover of Andrew Gelman, et al., Bayesian Data Analysis</figcaption>
</figure>
]

???

http://www.stat.columbia.edu/~gelman/book/