Ask Ghassem - Recent questions tagged probability

Which algorithm is best to detect anomalies within a data set of 5k+ user-login events?

Tue, 05 Oct 2021 17:45:38 +0000

I am trying to build an unsupervised ML model to detect anomalies within 5000+ users' login data. I selected 5 features contained within each of the user-login events (e.g. IP, hour of day, day of week, device_id, OS). I am looking for the best algorithm to use. I am considering using density function to determine probabilities of the feature values and whether an event is an outlier. The problem is that feature values are only relevant to the specific user. For example, you cannot compare login IP across users, login IP is only applicable to the user.
Ultimately, I want to detect events that are changes in a user login behavior, like different IP, day, hour, device_id, or OS, where the more features that have changed increase the probability of an outlier.
At this point, I am not sure how to build a model with data that contains multiple users, because I don't know how to separate the user data so the model is trained per user and finding anomalies within the individual user's features.

I also don't have any labeled data to use for testing, should I fabricate some?

Any advice greatly appreciated.

Thank you!

Probability of a bus arrived in its destination based on weather condition

Mon, 09 Nov 2020 13:06:47 +0000

A bus is making its way to a destination. If the weather conditions are favorable today, the likelihood of delay is 3%. If the weather conditions are not favorable today, the likelihood of delay is 50%. The forecast predicts that it is 20% likely that the weather conditions will be favorable today.

1. What is the likelihood that the bus will be delayed?

2. The bus has arrived, but it was delayed. Given that the bus was delayed, what is the likelihood that the weather conditions were favorable?

How to calculate the probability and accuracy of a Logistic Regression classifier?

Mon, 03 Feb 2020 20:31:49 +0000

How to solve this problem?

https://i.imgur.com/8urywpf.jpg

Q1) Complete the ? sections

Q2) Accuracy of system if threshold = 0.5?

Q3) Accuracy of system if threshold = 0.95?

How to calculate probability in Logistic Regression?

Mon, 18 Mar 2019 20:22:35 +0000

The dataset of pass/fail in an exam for 5 students is given in the table below. If we use Logistic Regression as the classifier and assume the model suggested by the optimizer will become the following for Odds of passing a course:

$\log (Odds) = -64 + 2 \times hours$

1) How to calculate the probability of Pass for the student who studied 33 hours?

2) At least how many hours the student should study that makes sure will pass the course with the probability of more than 95%?

Probability for the data items within mean +- 1, +-2, +-3 standard deviation?

Fri, 30 Nov 2018 21:15:35 +0000

What will be probability for the data items within mean +- 1, +-2, +-3 standard deviation?

Wed, 14 Nov 2018 15:10:15 +0000

How do we determine if two events are independent

Sat, 13 Oct 2018 15:23:39 +0000

In the context of probability, what is the "event space"

Sat, 13 Oct 2018 15:10:28 +0000

If x is the number that comes up when you roll a 20 sided die. What is the expected value of x?

Fri, 12 Oct 2018 22:43:05 +0000

If x is the number that comes up when you roll a 20 sided die. What is the expected value of x?

What is the probability of getting a King of Hearts?

Fri, 12 Oct 2018 22:31:45 +0000

What is the probability of picking a King of Hearts in a standard 52 card deck?

Two coins are flipped. What is the probability of getting heads twice?

Thu, 11 Oct 2018 23:49:03 +0000

A standard deck of 52 cards is shuffled and a single card is drawn. What is the probability that this card is a Joker

Mon, 01 Oct 2018 19:51:38 +0000

This is question 1d in the 2B exercises. The answer says the probability is 0 but I count 4 jokers in a 52 card deck, which means the probability is 1/13. Think I misunderstand the question. Why is it 0?