Problema:

Tutor

Welcome!  How are you?

Student

hello! good!

Tutor

Tell me, what can I do for you today?

Student

twell, im not sure how to find the standard error here for a difference in proportions

Tutor
ok, let’s find the proportions first, can you calculate them?

Student

.25 and .125

Tutor
Excellent!  You did that step perfectly. the formula for the SE is…
is that familiar to you?

Student
yeah, thats what i thought i originally did, i may have made a calculator error

Tutor
let’s check it together then. well done!
how much is the first term inside the square root?

Student

.0036

Tutor
perfect!
what about the second term?

Student
and .0012

Tutor
well done, if we add them we get 0.00485. right?

Student
and then we square root for .069!

Tutor
perfect!
check that the square root is 0.0696

Student
yup! i got .0693 but i think its close enough

Tutor
if we take the first three digits after the dot, the approximation is 0.070
Great job on that one! Nicely done.

Student
actually, unrounded i did get 696, awesome, thank you for your help!

Tutor
you are welcome , Do you have any questions about anything we went over today?

Student
nope, thanks again!

The post Error estándar en diferencia de porcentajes first appeared on LatinHire Online Tutoring.

Tutor
[00:00:10] Welcome! My name is Anahid, How are you?

Student
[00:00:44] hello im great how are you?

Tutor
[00:01:04] I’m great too! Thanks
[00:01:11] Tell me, what can I do for you today?

Student
[00:01:34] i wrote the problem up there ^
[00:01:39] i dont know what to do

Tutor
[00:02:00] are you familiar with the concept of correlation?

Student
[00:02:09] yes somewhat.

Tutor
[00:02:31] can you tell me what correlation means?

Student
[00:03:35] its a relationship or connection between two things
[00:03:41] if they are related or not..

Tutor
[00:03:52] that’s right!
[00:04:08] the correlation express the relation between two variables
[00:04:22] so if there is an almost zero correlation
[00:04:31] what that means?

Student
[00:04:57] there is no correlation

Tutor
[00:05:05] that’s right
[00:05:07] !
[00:05:25] here is a web site that can help use to see it better

Student
[00:05:59] ok great, thanks!

Tutor
[00:06:14] can you see the graphs?

Student
[00:06:23] yes

Tutor
[00:06:28] look at the one that says zero correlation
[00:06:49] we have two variables, each one represented by an axis
[00:07:35] can we predict one from the other?

Student
[00:07:56] theyre not related?

Tutor
[00:08:07] that’s right
[00:08:36] we can not predict one from the other
[00:08:49] those dots are random
[00:09:03] Does this problem make sense to you now?

Student
[00:09:27] yes
[00:09:38] but i dont get what independent
[00:09:42] or dependent mean

Tutor
[00:10:15] dependent means that the value of one variable depends on the value of the other
[00:10:23] independent is the opposite
[00:10:38] it means that the variables are not related

Student
[00:10:48] oh so a?
[00:10:51] independent

Tutor
[00:10:56] does this sound familiar to you?
[00:11:03] Great job on that one! Nicely done.

Student
[00:11:02] yes

Tutor
[00:11:15] Perfect!  Good work.
[00:11:21] Do you have any questions about anything we went over today?

Student
[00:11:24] thank you!
[00:11:30] no thats it

The post Correlaciones Lineales first appeared on LatinHire Online Tutoring.

La tutoría:

Student Question: Employment data at a large company reveal that 72% of workers are married, that 44% are college graduates, and that half of the college grads are married. What’s the probability that a randomly chosen worker is: a) neither married nor a college graduate? b) is married but not a college graduate? c) is married 9or a college graduate?

Tutor: Welcome! My name is Anahid. How are you?

Student: Good. U?

Tutor: I’m great! Thanks. Tell me, what can I do for you today?

Student: I have a entire assignment to do like the problem stated, and I’m not sure how to get it solved. I started with a contingency table, but that’s it…

Tutor: well done!

Student: that’s as far as i get….

Tutor: check that we also know the totals, how many of them are married?

well done!, check that married and not married must sum 100%
how many are not married?

Student: 56?

Tutor: well done!(but 56 is for not college)

Student: oh, sorry

Tutor: Very close — let’s take another look and see what we missed.
we are setting college graduates on the line
and married on the column

44% are college graduates

so 100%-44%=56% are not college graduates

Do you understand how we did that last part?

Student:  No
I do. the complimentary rule?

Tutor: that’s right!

Student: okay. I follow you now! :)

Tutor: let’s do the same with the married on the last column
72% are married, how much are not married?

Student: 28%

Tutor: Excellent!  You did that step perfectly.
Do you know what to do next?

Student: for college grad and not married, it would be 22%, is that correct?

Tutor: Perfect!  Good work.
what about for married and not college grad?

Student: 50%?

Tutor: Great job on that one! Nicely done.

Student: :D

Tutor: can you complete the table?
You got it!

Student: yay!

Tutor: now we are ready to answer the questions

Student: okay

Tutor: how much is the answer on letter a?

Student: 6% ??

Tutor: well done!
what about letter b?

Student: 50%

Tutor: Perfect!  Good work.
what about the last one?

Student: 31.7%?
72% x44%?

Tutor: Very close — let’s take another look and see what we missed.
let’s focus on the center of the table

Student: okay

Tutor: can you circle the ones that are married?
well done!
what about the ones that are college graduates?
well done!
if we were to find the ones that are married OR college grad we should add all the circles
how much will that be?

Student: 94%?

Tutor: Great job on that one! Nicely done.
Does this problem make sense to you now?

Student: or = addition?

Tutor: yes, but be careful, we did not add 44% and 72%

Student: haha… too much!!!
because they could be married and not grad, grad and not married, and married or grad… all three are feasable choices!!??

Tutor: that’s right, but if we added 44%+72% we will be counting the 22% od the intersection twice

Student: I get it!!! Makes sense now!

Tutor: check that 44%+72%-22%=94%
Do you have any questions about anything we went over today?

Student: No, everything was great!. Very good explanation of everything! Have a good evening!

Tutor: Thank you, Have a good evening too!

Colaboradora: Anahid Bauer, Tutora Argentina de Estadística

The post Conjuntos y Probabilidades: Ejemplo de una excelente tutoría de Estadística first appeared on LatinHire Online Tutoring.