Ask Ghassem - Recent questions in Statistics

How do I compare the count of a value in each year while having a different sanple size each year.

Wed, 08 Jun 2022 10:32:33 +0000

How do I accurately compare between the number of something a survey measure from my employees each year with a varying umber of survey engagement and employee size?

If I was measuring the satisfaction of my employees over the years by collecting a survey from my them each year by asking them wether they are satisfied or not, and then comparing yes’s over the years but the number of employees who answer is not the same each year and the number of employees increases every year. How do I correctly compare this throughout each year?

In other words, how do I remove the effect of the survey engagement rate when calculating the results?

is it possible to derive a new 95% CI from two separate 95% CIs?

Mon, 23 Nov 2020 14:45:19 +0000

Individual and group relative strength in a fixed pool of players: How to approach the problem?

Tue, 29 Oct 2019 20:00:28 +0000

I apologize in advance if my question sounds too basic to be worthy of anyone's time, but statistics are not part of my curriculum.

I am developing a proof of concept of a web application modeling the contribution of individual soccer player with respect to the different teams they've played with throughout their career. In particular, I am looking into a way of ranking both individuals and groups of players as follows::

teammates relative strength: the best/worst combinations of players when playing in the same team in the same matches;
opponents relative strength: the best/worst combinations of players when playing in opposite teams in the same matches, i.e. which tuples of teammates are the best/worst against which;

I must admit I don't quite know how to approach the problem (as I said I have no formal education in statistics or data science). I would be very grateful if anyone could give me some directions. How should I frame this particular problem and what resources in statistics or machine learning (if indeed this is a task fit for machine learning, perhaps I am mistaken on this) would be appropriate to tackle it?

I am eager to learn, so both practical examples or theoretical references (book chapters, online articles, etc) would be very welcome.

Thanks in advance!

Using aggregate data to generate observation-level data statistically sound?

Tue, 11 Jun 2019 22:04:01 +0000

Context: In the realm of Paid Search Marketing. Current reporting does not provide event level data only aggregate totals with different segments. Want to compare distributions/test statistical significance of A/B test results. Did not want to assume that data followed normal distribution or know STDEV for data so came with this approach.

My Question: I am going to use the average "CPA" or "CTR" for a date range, and generate an observation for each conversion based off the average for a time range. Is this statistically sound way if I want to generate raw data? Would I have wonky distributions because of the multiple averages? Just want a gutcheck if I'm completely off base.

My Aggregate data looks like below:

Day	Cost	Acquisition	CPA or CTR
1	40	2	$20
2	75	3	$25

Observation data I generate looks like below:

Day	Acquisition
1	$20
1	$20
2	$25
2	$25
2	$25

I really appreciate your help with this question! An important project to me at work.

nonpooled independent samples t-interval method

Fri, 07 Dec 2018 23:06:04 +0000

Computing the Confidence Interval for a Difference Between Two Means

Fri, 07 Dec 2018 23:02:45 +0000

How to find the strength of a P-value against a null hypothesis?

Fri, 07 Dec 2018 22:31:33 +0000

What is degree of Freedom while calculating confidence interval?

Fri, 07 Dec 2018 22:27:27 +0000

How do you know when to use T-Distribution instead of regular Confidence Interval?

Wed, 05 Dec 2018 22:50:48 +0000

What is the T Distribution?

Fri, 30 Nov 2018 21:22:02 +0000

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

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

How do I calculate a and z a/2?

Thu, 29 Nov 2018 18:19:23 +0000

What is the rule that determines percentages with the mean +- 1,2 or 3 standard deviations?

Sat, 17 Nov 2018 19:03:35 +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 much percentage of data items are consumed within mean +-1 , +-2, +-3 standard deviation?

Wed, 14 Nov 2018 15:04:52 +0000

What is a test statistic in hypothesis testing and how does it relate to the p-value?

Tue, 13 Nov 2018 00:51:11 +0000

What is sampling error?

Tue, 13 Nov 2018 00:47:51 +0000

What is P-value in Statistical Testing?

Mon, 12 Nov 2018 13:41:39 +0000

What is P-value in Statistical testing?

What is a sampling distribution of sample means?

Mon, 12 Nov 2018 13:38:30 +0000

What is a sampling distribution of sample means?

In the first week of November 2003.... What is the expected number of homicides per week in the GTA?

Fri, 02 Nov 2018 19:34:40 +0000

This is from question one from lecture 4B's exercises: "In the first week of November 2003, five unrelated homicides were reported in the GTA. The GTA usually has about 78 homicides per year. What is the expected number of homicides per week in the GTA?"

In statistics, whats the difference between contingency and frequency tables?

Tue, 30 Oct 2018 11:19:48 +0000

How to discover outliers of a data frame?

Sun, 28 Oct 2018 11:20:51 +0000

How do you tell a permutation problem from a combination problem?

Mon, 15 Oct 2018 15:34:13 +0000

Given the questions:

1. How many different groups of 4 students can be made from a class of 40?

and

2. How many different lists of 4 students can be made from a class of 40?

How do you determine which requires a permutation and which requires a combination?

What is the use of the Poisson Distribution?

Sat, 13 Oct 2018 15:37:29 +0000

Also, when would one use this distribution ?

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

What is the "Three-Standard-Deviations Rule"

Sat, 13 Oct 2018 14:57:53 +0000

This rule is also known as the "68–95–99.7 rule". What does this rule stand for and how does it help me?

How do histograms help us understand a data set?

Sat, 13 Oct 2018 14:42:11 +0000

What is a discrete random variable?

Sat, 13 Oct 2018 01:23:24 +0000

What is the difference between permutation and combination?

Sat, 13 Oct 2018 01:19:28 +0000

What is the difference between Qualitative and Quantitative data?

Sat, 13 Oct 2018 01:15:59 +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?

Define measures of center (Median and Mode) ?

Fri, 12 Oct 2018 22:28:59 +0000

Define the 2 measures of centers.

What is "Random Sampling"?

Fri, 12 Oct 2018 22:26:06 +0000

Define random sampling

What is binomial experiment and when do we use it?

Fri, 12 Oct 2018 22:25:59 +0000

When should we use permutation and combination?

Fri, 12 Oct 2018 22:16:45 +0000

Calculate IQR(Inter Quartile Range) of {18, 24, 19, 16, 21}?

Fri, 12 Oct 2018 22:07:58 +0000

What do population, parameter, census and sample mean in statistics?

Fri, 12 Oct 2018 21:50:34 +0000

Question for Discrete random variable

Fri, 12 Oct 2018 21:00:40 +0000

An investor has a 0.60 probability of making a 20000 dollar profit and a 0.40 probability of suffering a 25000 dollar loss. What is the expected value?

Sample question of permutation and combination.

Fri, 12 Oct 2018 20:47:03 +0000

You can bring along 2 friends! you have 5 friends who want to come along. How many different groups of friends could you take with you?

{1.75, 1.63, 1.55, 1.92, 1.81, 1.79, 1.81}. Determine the mean, the median, and the 20th percentile?

Fri, 12 Oct 2018 19:42:32 +0000

What is difference between discrete numerical variable and continuous numerical variable?

Fri, 12 Oct 2018 19:25:11 +0000

What is the mean and standard deviation of a standard normal distribution?

Fri, 12 Oct 2018 01:39:12 +0000

Find the expected value of X from the probability table.

Fri, 12 Oct 2018 01:33:43 +0000

Find the expected value of X from the probability table.

X	1	2	3
P(X)	0.3	0.8	0.4

How many unique ways are there to arrange the letters in the word PRIOR?

Fri, 12 Oct 2018 01:22:26 +0000

If a die is rolled, find the probability of rolling an even number

Fri, 12 Oct 2018 01:15:55 +0000

What is the difference between Descriptive Statistics and Inferential Statistics?

Fri, 12 Oct 2018 01:02:35 +0000

What is the Empirical Rule?

Fri, 12 Oct 2018 00:36:57 +0000

A gambling machine accepts 5 dollars and generates a random dollar value (x) between 1 and 10.

Fri, 12 Oct 2018 00:21:18 +0000

A gambling machine accepts 5 dollars and generates a random dollar value (x) between 1 and 10.

What is the distribution of x?
What is the expected value of x?
Is it smart to use this gambling machine?