# Search results

1. ### Margin of Error of a Confidence Interval

This question is similar to your question: http://statkat.com/statquestion.php?q1=10&s1=10&q2=32&s2=10&q3=33&s3=10&q4=55&s4=10&q5=56&s5=10&q6=57&s6=10&q7=151&s7=10&q8=152&s8=10&q9=163&s9=10&qx=9 . The explanation that accompanies the question will probably help you solve the problem.
2. ### making R computing large factorials

p.x.log <- function(n.of.points, x, p, q) { log.result <- sum(log(n.of.points:1)) - sum(log(x:1)) - sum(log((n.of.points-x):1)) + x*log(p) + (n.of.points-x)*log(q) exp(log.result) }
3. ### making R computing large factorials

You could do the computations in log space

5. ### Minimise chance of making type 1 error, without reducing alpha?

Alpha = the probability of making a Type I error...
6. ### Anova

I agree with ondansetron that reading a bit more about ANOVA in your textbook could help you a lot with answering the questions. However, if you prefer practice questions where the correct answer is explained, you may want to have a look here: http://statkat.com/selectquestions.php . You can...
7. ### Coefficient of correlation.

That's correct. Also, note that dividing the values by 5 is the same as multiplying them by 1/5. So in de second question, the x values are multiplied by 2/5 (and 3/5 is added to them).
8. ### Coefficient of correlation.

Well, the coefficient is determined by the strength and the direction of the linear relationship between two variables. If there is a linear negative relationship between two variables, the coefficient is between 0 and -1. If there is a linear positive relationship between two variables, the...
9. ### Coefficient of correlation.

Then I disagree with that source. I think they made a mistake.
10. ### Coefficient of correlation.

A is the correct answer for the second question. It seems like you get it!
11. ### Coefficient of correlation.

At the bottom of this overview http://statkat.com/stattest.php?t=19 you can find a list of properties of the correlation coefficient. The property listed fourth can help you answering this question. Let me know if you can figure it out using this information.
12. ### How to know if I should use correlation or hypothesis test?

I wouldn't say the order matters.
13. ### How to know if I should use correlation or hypothesis test?

I think the 'trick' is to really understand what each method/test is for (e.g., one sample t test tests whether an unknown population mean mu is different from a certain fixed value, two sample t test tests whether an uninown population mean is different from another unknown population mean...
14. ### How to know if I should use correlation or hypothesis test?

This website allows easy comparison of several tests: http://www.statkat.com/stattest.php?&t=10&t2=9&t3=19 . You can remove/add methods to compare with each other if you like. It might be useful for you!
15. ### track data across quartile groups (if that's even a thing)

Ah I hadn't seen your last message when I posted my new response... Yes that is what I was suggesting. I assumed you had already done this
16. ### track data across quartile groups (if that's even a thing)

Maybe I get it now. You have three variables (which you call categories, that got me confused), the first ranging from -36 to 36, the second from 0 to 760, and the third from 0 to 38. You have transformed each variable into an ordinal variable consisting of four quartiles. Now you want to know...
17. ### track data across quartile groups (if that's even a thing)

One the one hand, it sounds like all variables are ordinal (four ordered quartiles), and you want to know whether people scoring in lower quartiles on one variable, also score in lower quartiles on the other variable (and same for higher quartiles). Spearman's rho would be a useful measure in...
18. ### track data across quartile groups (if that's even a thing)

Maybe Spearman's rho for the relationship between two ordinal variables can be useful here.
19. ### Need help with hypothesis question

I went with the z test because the alternative hypothesis was one sided. If the alternative hypothesis had been two sided (rate is different between the two groups, no specified direction of the difference), you could just as well have performed the chi-squared test. The p value resulting from...
20. ### Need help with hypothesis question

It looks like they want you to perform a z test for the difference between two proportions,see: http://statkat.com/stattest.php?t=2