SOCI 3311 Blog

Two variables are said to be INDEPENDENT if knowledge of one does not affect one's prediction of the value the other will assume.

CHI SQUARE is a measure of how much observed and expected frequencies deviation from one another.

thank you but i got it after a while. i knew it was simple but i just couldn't get the words out

This problem is actually similar to problem 4.

Here is the difference.

In problem 4, you are given the sample mean. In problem 5, you are given the sample and you will need to compute the sample mean (use the DESCRIPTIVE STATISTICS calculator for this).

Once you compute the sample mean, work the problem exactly as you worked problem 4.

To read area using the standard normal curve, 2 z scores are required.

For example, to read area between z = 0 and z = -1, enter 0 in one box and -1 in the other. It doesn't matter which box has the 0 and which box has the -1. Then click READ AREA.

To read area ABOVE z = 1.00, theoretically your second boundary is ∞. However, the calculator cannot work with ∞. So you need to enter a real number. Since we know virtually 100% of area lies between z = -4 and z = +4, any number above +4 will work to give us four digits of accuracy. Hence, to read the area ABOVE Z = +1, enter 1 in one box and 5 in the second box. Then click READ AREA.

Likewise, to read area BELOW Z = 1, theoretically, the second boundary is -∞. Let's substitute -5 for this and hence, you would enter 1 in one box and -5 in the second box. Then click READ AREA.

Remember, if you are given 2 z scores, simply enter those two z scores and then click READ AREA.

If you are asked to read the area ABOVE Z, make 5 your second z score.

If you are asked to read the area BELOW Z, make -5 your second z score.

OK, Dr. Guy, i got it and thank you very very much, but for the other homework question i missed, can you please just give me a brief explanation of what i did wrong, becuase i was truely want to know where i went wrong in finding the answers.

The Sampling Distribution of Sample Means

Thank you so much...I did this, but I got really nervous because I hate math and everything that looks like it.....I was really overthinking the problem. Thank you

You're welcome. :)

Thank you for the explanation. I was struggling with that problem as well.

Solving this problem requires the use of the computational formula for population variance.

Please see Formula 4.5 (Unit 4).

You are told ∑X² = 150.

You are also told ∑X = 25 and N=10.

Hence, the first term in the numerator is replaced with 150.

To compute the second term in the numerator we need to square 25 and then divide the squared value by 10. 25² = 625 and 625/10 = 62.5.

Now to complete our computations in the numerator we must subtract: 150 - 62.5 or 87.5.

This numerator must now be divided by N or 10.

Final Answer will be 87.5/10. You can finish out this math.

Thanks Dr. Guy

The scores closest to the mean have the greatest effect on the standard deviation and variance.

This statement is FALSE.

Remember, the standard deviation & variance are computed using squared deviations from the mean. The greater the distance between a score and the mean, the larger the deviation and squared deviation. Hence, it is the scores farthest from the mean (greatest distance) that have the greatest effect on the standard deviation and variance.

I've copied and pasted this from a Februrary 2009 blog entry:

Please check all blog entries for lots of homework help.

These four problems require use of the ONE SAMPLE Z calculator. Once you have computed z, use the following format to report your answer:

State the null and research hypotheses
State the level of significance (given in problem)
State the critical value of z (linked to the level of significance)
State the obtained (or calculated) value of z
State your decision

For Problem 4, your answer should appear as follows:

H(0): μ = 100
H(1): μ ≠ 100
α = .01
z critical = ±2.58
z obtained = 3.33
Decision: Reject H(0) and Accept H(1)

Use the same format for problems 5, 6, & 7.

For problem 5, you will need to first use the DESCRIPTIVE CALCULATOR to find the sample mean and sample standard deviation before you can use the ONE SAMPLE Z CALCULATOR.

All of this is explained in Unit 7.

i forgot about the past blogs. thanks for replying

For parts 1, 2, & 3, you will need to convert the raw scores listed to z score form and then read the appropriate area in the standard normal curve.

For part 4, read the area between z = -1 and z = +1.

For part 5, read the area between z=-2 and z=+2.

Once you have area for these problems, don't forget to multiply that area by 100 to convert it to a percent.

thank you! i think i knew how to do it, just didn't know how to start

From the past blogs she said just to put them into 5 columns

Don't worry about the columns not lining up. Just leave a couple of spaces between each column (aF, caF, rF, crF) and I will be able to understand your answer.

the answer is on page 28 of unit 2 if seen from the site page by page.

Yes.

I found it.
Thanks

Since the mean is SMALLER than the median, it is likely skewed to the LEFT. With so little data, there is no way to know for certain but NEGATIVELY skewed would appear to be the best answer.

thanks