Cub Foods - Inferential Statistics, Question 2

Bertha Weaver, James Wooley, Mary Songer, Bill Jones
Math 113 - 01: Spring 2000

Is the sale price for Cub Foods significantly cheaper than the regular price?

T-Test Comparing Regular Price and Sale Price for all Products

Paired Samples Statistics

Mean N Std. Deviation Std. Error Mean
Pair 1 Regular Price 2.2759 37 1.4443 .2374
Price Paid 2.0630 37 1.3446 .2210




Paired Samples Test

Paired Differences t df Sig. (2-tailed)
Mean Std. Deviation Std. Error Mean

Regular Price - Price Paid .2130 .5560 9.141E-02 2.330 36 .026

With a p-value of 0.013, the sale price is significantly cheaper than the regular price.

T-Test Comparing Regular Price and Sale Price, by Product Category

Paired Samples Statistics
Product Category Mean N Std. Deviation Std. Error Mean
Dairy Products Pair 1 Regular Price 3.6100 3 1.0923 .6307
Price Paid 3.5067 3 1.2163 .7022
Beverages Pair 1 Regular Price 3.1333 6 2.4901 1.0166
Price Paid 2.4433 6 2.4398 .9960
Breakfast Cereals Pair 1 Regular Price 2.9138 8 .4557 .1611
Price Paid 2.5338 8 .4613 .1631
Snacks and Sweets Pair 1 Regular Price 2.2520 5 1.0946 .4895
Price Paid 2.1740 5 1.0962 .4903
Fruits and Fruit Juices Pair 1 Regular Price 1.7240 5 .9895 .4425
Price Paid 1.7240 5 .9895 .4425
Lunch Meat Pair 1 Regular Price 1.0400 4 .3000 .1500
Price Paid 1.0400 4 .3000 .1500
Soups and Sauces Pair 1 Regular Price .7625 4 .1972 9.860E-02
Price Paid .7625 4 .1972 9.860E-02
Meats Pair 1 Regular Price 2.0900 2 1.1314 .8000
Price Paid 2.0900 2 1.1314 .8000










Paired Samples Test

Paired Differences t df Sig. (2-tailed)
Mean Std. Deviation Std. Error Mean
Product Category
Dairy Products

.1033 .1790 .1033 1.000 2 .423
Beverages

.6900 1.0536 .4301 1.604 5 .170
Breakfast Cereals

.3800 .6545 .2314 1.642 7 .145
Snacks and Sweets

7.800E-02 .1744 7.800E-02 1.000 4 .374

There were no items that were on sale for the following product categories:
	Fruits and Fruit Juices
	Lunch Meat
	Soups and Sauces
	Meats
Since there is no differences in prices, the sale price is not cheaper than the regular price.

Also, since no p-value is less than 0.05, none of the sale prices are cheaper by category.

It is interesting to note that although no one product category is signficantly cheaper, overall, the sale price is cheaper than the regular price.