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Placer.ai Interview Questions

A/B Testing

Algorithms

Analytics

Machine Learning

Probability

Product Metrics

Python

Statistics

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<p>The table <code>packet_rates</code> contains data about wireless packages sent from multiple devices to different networks (SSID).</p>

<p>Write a query that returns, for each SSID, the largest number of packages sent by a single device in the first 10 minutes of January 1st, 2022.</p>

<p><strong>Example:</strong></p>

<p><strong>Input:</strong></p>

<p><code>packet_rates</code> table</p>

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>packet_id</code></td>
<td>INTEGER</td>
</tr>

<tr>
<td><code>ssid</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>mac_address</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>time_captured</code></td>
<td>DATETIME</td>
</tr>

<tr>
<td><code>packet_size</code></td>
<td>INTEGER</td>
</tr>
</tbody>
</table>
<p><strong>Output:</strong></p>

<table>
<thead>
<tr>
<th>Column</th>
<th>Type</th>
</tr>
</thead>

<tbody>
<tr>
<td><code>ssid</code></td>
<td>VARCHAR</td>
</tr>

<tr>
<td><code>max_number_of_packages_sent</code></td>
<td>INTEGER</td>
</tr>
</tbody>
</table>


Write a query that returns, for each SSID, the largest number of packages sent by a single device in the first 10 minutes of January 1st, 2022.

Largest Wireless Packages

<p>Suppose there exists a new airline named Jetco that flies domestically across North America. Jetco recently had a study commissioned that tested the boarding time of every airline, and it came out that Jetco had the fastest average boarding times of any airline.</p>

<p>What factors could have biased this result, and what would you look into?</p>


<p>What could potentially bias the average boarding time in favor of an airline that only flies domestically?</p>

What could potentially bias the average boarding time in favor of an airline that only flies domestically?

Boarding Times Bias

A new airline came out as the fastest average boarding times compared to other airlines.  What factors could have biased this result and what would you look into?

<p>You are testing hundreds of hypotheses with many <em>t</em>-tests. What considerations should be made?</p>


<p>What is a key disadvantage of the F-test when compared to multiple t-tests?</p>

What is a key disadvantage of the F-test when compared to multiple t-tests?

Hundreds of Hypotheses

You are testing hundreds of hypotheses with many t-tests. What considerations should be made?

Question	Topic	Difficulty	Ask Chance
Largest Wireless Packages	SQL	Easy	Very High
Boarding Times Bias	Statistics	Medium	Medium
Hundreds of Hypotheses	Statistics	Medium	Medium