Question

In the week 2 lab, you found the mean and the standard deviation for the HEIGHT variable for both males and females. Use those values for follow these directions to calculate the numbers again.

(From week 2 lab: Calculate descriptive statistics for the variable Height by Gender. Click on Insert and then Pivot Table. Click in the top box and select all the data (including labels) from Height through Gender. Also click on “new worksheet” and then OK. On the right of the new sheet, click on Height and Gender, making sure that Gender is in the Rows box and Height is in the Values box.   Click on the down arrow next to Height in the Values box and select Value Field Settings. In the pop up box, click Average then OK. Write these down. Then click on the down arrow next to Height in the Values box again and select Value Field Settings. In the pop up box, click on StdDev then OK. Write these values down.)

You will also need the number of males and the number of females in the dataset. You can either use the same pivot table created above by selecting Count in the Value Field Settings, or you can actually count in the dataset.

Then in Excel (somewhere on the data file or in a blank worksheet), calculate the maximum error for the females and the maximum error for the males. To find the maximum error for the females, type =CONFIDENCE.T(0.05,stdev,#), using the females’ height standard deviation for “stdev” in the formula and the number of females in your sample for the “#”. Then you can use a calculator to add and subtract this maximum error from the average female height for the 95% confidence interval. Do this again with 0.01 as the alpha in the beginning of the formula to find the 99% confidence interval.

Find these same two intervals for the male data by using the same formula, but using the males’ standard deviation for “stdev” and the number of males in your sample for the “#”.

1. Give and interpret the 95% confidence intervals for males and females on the HEIGHT variable. Which is wider and why? (7 points)

2. Give and interpret the 99% confidence intervals for males and females on the HEIGHT variable. Which is wider and why? (7 points)

Height (inches)	Gender
65	F
67	F
65	F
63	F
66	F
63	F
66	F
69	F
68	F
65	F
67	F
64	F
63	F
63	F
69	F
62	F
63	F
70	F
75	F
61	M
61	M
73	M
69	M
70	M
68	M
65	M
66	M
68	M
70	M
66	M
70	M
69	M
63	M
74	M
75	M

Answer 1

mean and the standard deviation for the HEIGHT variable for both males and females.

Fomulas:

Sample Size	=COUNT(A2:A36)
Mean	=AVERAGE(A2:A36)
Standard Deviation	=STDEV(A2:A36)

Calculate descriptive statistics for the variable Height by Gender

Descriptive statistics by gender. So separate the data set as per the gender.

Female Descriptive statistics:

1. First bring female data set alone in excel sheet.

2. Go To data tab in the ribbaon and choose data analysis. Next choose descriptive statistics in the statistics list and click ok.

Followe the below step to get the descriptive stat.

Female- STat

Follow the same step to get descriptive statistics for Male heights.

(Sekect only male data set)

Find average, stdev and count from pivot table

Average:

Select the data set completely and click insert option and choose pivot table option.

In the value field settings (you can see in the above snap) Average,Standard deviation and count will be available

AVerage:

Row Labels	Average of Height (inches)
F	65.95
M	68.00
Grand Total	66.88571429

Standard deviation:

Row Labels	StdDev of Height (inches)
F	3.24
M	4.20
Grand Total	3.794511738

Count:

Row Labels	Count of Height (inches)
F	19.00
M	16.00
Grand Total	35

95 and 99 % confidence interval:

WE have already created sample size, mean and standard deviation in the first image.

Now we can make use of that and create confidence interval

95% = (65.6, 68.1)

99% (65.2, 68.5)

Formula REference:

so margin error calculate with the formula of "=confidence(significant level, standard deviation, sample size)