Question

An article described an experiment in which observations on various characteristics were made using minichambers of three different types: (1) cooler (PVC frames covered with shade cloth), (2) control (PVC frames only), and (3) warmer (PVC frames covered with plastic). One of the article's authors kindly supplied the accompanying data on the difference between air and soil temperatures (°C).

Cooler	Control	Warmer
1.59	1.92	2.57
1.43	2.00	2.60
1.88	2.19	1.93
1.26	1.12	1.58
1.91	1.78	2.30
1.86	1.84	0.84
1.90	2.45	2.65
1.57	2.03	0.09
1.79	1.52	2.74
1.72	0.49	2.53
2.41	1.90	2.13
2.34		2.86
0.78		2.31
1.34		1.91
1.76

(a)

Compare measures of center for the three different samples.

Cooler   

Control

Warmer   

(b)

Calculate the standard deviations for the three different samples. (Round your answers to three decimal places.)

Cooler s = 4 Control s = 5 Warmer s = 6

Interpret and compare the standard deviations for the three different samples.

We see from the standard deviations that variability increases when the conditions of of the mini-chambers transitions from the cooler to the control and decreases when the conditions transition from the control to warmer. We see from the standard deviations that variability increases as the conditions of the minichambers transition from warmer to cooler.     We see from the standard deviations that variability increases as the conditions of the minichambers transition from cooler to warmer. We see from the standard deviations that there is no difference in variability between the three conditions. We see from the standard deviations that variability decreases as the conditions of the minichambers transition from cooler to warmer.

(c)

Do the fourth spreads for the three samples convey the same message as do the standard deviations about relative variability?

Yes, The fourth spreads do communicate the same message as the standard deviations did.

No, The fourth spreads do not communicate the same message as the standard deviations did.    

Answer 1

a)using median function from excel:

Cooler median=		1.76
Control median=		1.9
warmer median=		2.305

b)using stdev function from excel:

Cooler s=		0.409
Control s=		0.541
warmer s=		0.784

We see from the standard deviations that variability increases as the conditions of the mini chambers transition from cooler to warmer.

c)

Yes, The fourth spreads do communicate the same message as the standard deviations did.