Manuals/calci/ZTESTEQUALMEANS

ZTESTTWOSAMPLEFORMEANS(ar1,ar2,v1,v2,md,alpha,lv)

• $ar1$ and $ar2$ are array of values.
• $v1$ and $v2$ are value of variances.
• $md$ is the Hypothesized Mean Difference.
• $alpha$ is the significance level.
• $lv$ is the logical value.

Description

• This function gives the z-test two sample for means.
• We can use this test when

1.The samples can be different sizes.
2.The two samples are independent.
3.Both populations are normally distributed or both sample sizes are large enough that the means are normally distributed.

• In $ZTESTTWOSAMPLEFORMEANS(ar_{1},ar_{2},v_{1},v_{2},md,alpha,lv)$,$ar_{1}$ and $ar_{2}$ are the set of values,$v_{1}$ is the variance of $ar_{1}$,$v_{2}$ is the variance of $ar_{2}$.
• $md$ is the Hypothesized Mean Difference. If testing is for equal means,then $md=0$.
• $alpha$ is the significance level which ranges from 0 to 1.
• $lv$ is the logical value like TRUE or FALSE.TRUE is indicating the result will display in new worksheet.
• Suppose we are omitted the $lv$ value it will consider the value as FALSE.
• ZTEST two sample for means is calculated by:$z={\frac {{\bar {x_{1}}}-{\bar {x_{2}}}-\Delta }{\sqrt {{\frac {\sigma _{1}^{2}}{n_{1}}}+{\frac {\sigma _{2}^{2}}{n_{2}}}}}}$

where ${\bar {x_{1}}}$ and ${\bar {x_{2}}}$ are average of two samples, $\Delta$ is the Hypothesized Mean Difference between two means of the population. $\sigma _{1}$ and $\sigma _{2}$ are the standard deviation of two population. $n_{1}$ and $n_{2}$ are the sizes of the samples.

• This function will give the result as error when

 1. any one of the argument is nonnumeric.
 2. alpha>1

Examples

1. Example 1

Spreadsheet

	A	B
1	70.25	90.02
2	82.87	89.45
3	90.17	70.89
4	45.55	107.91
5	51.98	59.09
6	21.28	45.03
7	39.04	56.08
8	40.47	91
9	30.02	40.41
10	100.05	29.04
11	86.1	37.79
12	72.49	41.07
13	29.54	52.04
14	38.76	60.78
15	47.01	66.06
16	50.65	78.01
17	55.91	41.22
18	102.7	33.99
19	10	110.02

1. =ZTESTTWOSAMPLEFORMEANS(A1:A18,B1:B19,641.8474654,630.283176,0,0.5)

Result

z-TEST: TWO SAMPLE FOR MEANS

	VARIABLE1	VARIABLE2
MEAN	56.04421052631579	63.152631578947364
KNOWN VARIANCE	641.8474654	630.283176
OBSERVATIONS	19	19
HYPOTHESIZED MEAN DIFFERENCE	0
z VALUE	-0.8687285374505475
P(T<=+t) ONE-TAIL	0.1924981032229391
z CRITICAL ONE-TAIL	0
P(T<=t) TWO-TAIL	0.3849962064458782
z CRITICAL TWO-TAIL	0.6744897501960817

Related Videos

Z-TEST Two Sample For Means

See Also

• ZTEST
• TTEST
• TINV

References

• Ztest Comparing two means