Math (Prof. Frank ONLY)

1) As per SLP3 expectation you have to prepare a frequency distribution of your collected data set. For that you can follow the following link or any other link from Module 3-Background.

http://campus.houghton.edu/orgs/psychology/stat3/

If you need extra help find the attachment. I have given the frequency distribution and constructed the histogram of a sample data set.

     Below is the data set with class width 8 when the data set is the no. of emails 11, 20,24,20,21,9,31,41,26,21 (for example).

     You choose your class width and build yours .If the 1st interval is 0-5 next one is going to be 6-11 and then follow the others.

Intervals	frequency
0-7	0
8-15	2
16-23	4
24-31	3
32-39	0
40-49	1

  Simply highlight the two columns, click on insert and then column chart in excel.

 

2)  Find out the variance and the standard deviation of the grouped distribution of your own data set (like #5 Case). I have sent out the sample example unlike #5 with  Case-3.

3) As you have the histogram now, imagine the curve going over your histogram. If the shape of the curve is approximately bell shaped then the distribution refers to normal distribution. It could be positively/negatively skewed. Figure that out. If mean is less than the median then the curve is negatively skewed or skewed left otherwise it is positively skewed.

 

You might check for outliers but pictorial view of the curve is the first instinct to infer the normality. Data set with outliers is not normally distributed.

4) Your curve might or might not be normal.

   If it is normal mention the empirical rule otherwise known as 68-95-99.7 rule. The rule says "The area under the part of the normal curve that is within 1 standard deviation is approximately 68%; within 2 standard deviations about 95%; and within 3 standard deviations about 99.7%". You need to describe your bell curve taking your mean and SD into account using empirical rule.