Question

A company sells its product line in traditional brick and mortar stores as well an online store site. Historically, 42% of all company sales took place through its online store site. Due to recent budget cuts, the company has had to cut back on advertising expenditures that promote the online store site. You would like to determine if there has been a DECREASE in the proportion of sales coming from the online store site since the time you reduced your advertising expenditures. Therefore, the null and alternative hypotheses are:

                               

                                H₀: proportion of online sales ≥ 42%         (no decrease in online sales proportion)

                                H₁: proportion of online sales < 42%         (decrease in online sales proportion)

You take a sample of 84 days and record what proportion of sales were online and what proportion were offline (in a traditional brick and mortar store). You utilize Minitab to create the analytics. The Minitab output is shown below.

Test and CI for One Proportion: ONLINE/OFFLINE

Method

Event: ONLINE/OFFLINE = ONLINE

p: proportion where ONLINE/OFFLINE = ONLINE

Exact method is used for this analysis.

Descriptive Statistics

N	Event	Sample p	95% Upper Bound for p
84	34	0.404762	0.500299

Test

Null hypothesis	H₀: p = 0.42
Alternative hypothesis	H₁: p < 0.42

P-Value

0.434

Find the p-value on the Minitab output. At a 95% confidence level, what is your conclusion regarding whether or not your company has experienced a decrease in the proportion of sales coming from the online store site. Justify your conclusion using the analytics.

Answer 1

MINITAB OUTPUT

Test and CI for One Proportion

Test of p = 0.42 vs p < 0.42

Sample X N Sample p 95% Upper Bound Z-Value P-Value
1 34 84 0.404762 0.492853 -0.28 0.389

Using the normal approximation.