The Hot dogs Story

Description

People who are concerned about their health may prefer hot dogs that are low in salt and calories. The "Hot dogs" datafile contains data on the sodium and calories contained in each of 54 major hot dog brands. The hot dogs are classified by type: beef, poultry, and meat (mostly pork and beef, but up to 15% poultry meat).
Variable Description
Type Type of hot-dog "stuffing" (Beef, Poultry and Meat)
Calories Calories per hot dog
Sodium Milligrams of sodium per hot dog

Source

Moore, David S., and George P. McCabe (1989). Introduction to the Practice of Statistics.
Original source: Consumer Reports, June 1986, pp. 366-367.

What to do

  1. Input data from file HotDogs.sav to SPSS.
  2. Make a scatterplot of X=Sodium and Y=Calories with markers set by Type.
  3. Are the samples normal distributed within each hotdog-type?
  4. Procduce Box-plots and Errorbar plots for Sodium and Calories.
  5. Compare all groups by an ANOVA-analysis.
  6. Run the ANOVA-analysis with a Bonferroni post-hoc test.

Analysis

A simple ANOVA model with type as the independent variable and calories as the dependent variable has an F-ratio of 16.074 , which is highly significant. Post-ANOVA analysis of group means shows that meat and beef hot dogs have approximately the same number of calories and poultry hot dogs generally have fewer calories than either beef or meat hot dogs.

The same model with sodium as the dependent variable has an overall F-ratio of 1.78, which is not significant. None of the individual differences are significant.