Question

A data set is provided, entitled oldfaithful_asst, on the duration and height of the Old

Faithful geyser in the Yellowstone National Park.

a.

Construct a scatterplot using Excel or any software (SPSS or Minitab)

between the variables “duration” and “height.” Please title the graph

“Scatterplot 1 Old Faithful” and create labels for both axes.

b.

There seems to be a an outlier in the data set. Although an outlier is not a

detriment to the data analysis, as part of an exercise, identify the outlier and

delete it (simply erase its value, do not replace with zero).



Show the new (second) scatterplot and title the graph “Scatterplot 2

Old Faithful”



Describe

the pattern that emerges.

What might this relationship

imply?

c.

Compute the correlation coefficient between the two variables and interpret

this correlation. Refer to both the strength and direction of the correlation in

your interpretation. Also interpret the correlation in terms of r-squared

(coefficient of determination).

d.

Conduct a regression to predict duration of an eruption using height and

interpret the sample slope coefficient in words.

e.

What is the predicted duration for an eruption that is 115?

Duration	Height
240	140
237	140
250	148
243	130
255	125
120	110
260	136
178	125
259	115
245	120
234	120
213	120
255	150
235	140
250	136
110	120
245	148
269	130
251	130
234	136
252	130
254	115
273	136
266	130
284	138
252	120
269	120
250	120
261	95
253	140
255	125
280	130
270	130
241	110
272	110
294	125
440	250

Answer 1

a) by using given data we can draw the scatter plot:b)

scatterplot old1 faithfull 300 minutes 250 minutes 200 minutes 150 minutes 100 minutes 50 minutes 100 cm 200 cm 225 cm 250 cm 125 cm 150 cm 175 cm 178 259 245 234 213 255 235 250 110 245 269 251 234 252 254 273 266 284 252 269 25 - (best line) Series 1 meta-chart.com 120 120 150 140 136 120 148 130 130 136 130 115 136 130 138

Scatterplot 2 old Faithful i can do in another software:

d) the regression equation is

Scatterplot 2 Old Faithful 300 250 200 150 100 100 90 110 120 130 140 150 Height Duration 은

duration = 212.6+0.26*(height)

if height increases the amount of duration also increases.

f) the predicted value of duration if height =115

= 212.6+0.26*115

=24478.9