Null-hypothesis for Kruskal-Wallis Test (Conceptual)

Explain

To illustrate how to write a null-hypothesis for a Kruskal-Wallis Test, let’s consider the following example:

Problem #1

A pizza café owner wants to know who eats more slices of pizza: football, basketball, or soccer players.

A pizza café owner wants to know who eats more slices of pizza: football, basketball, or soccer players. With this information she will determine how much inventory she needs during football and basketball seasons.

A pizza café owner wants to know who eats more slices of pizza: football, basketball, or soccer players. With this information she will determine how much inventory she needs during football and basketball seasons. She asks you to set up a study, collect the data, run the analysis and interpret the results for her.

A pizza café owner wants to know who eats more slices of pizza: football, basketball, or soccer players. With this information she will determine how much inventory she needs during football and basketball seasons. She asks you to set up a study, collect the data, run the analysis and interpret the results for her. After collecting the data you realize that there are some extreme outliers among basketball players that may skew the results.

A pizza café owner wants to know who eats more slices of pizza: football, basketball, or soccer players. With this information she will determine how much inventory she needs during football and basketball seasons. She asks you to set up a study, collect the data, run the analysis and interpret the results for her. After collecting the data you realize that there are some extreme outliers among basketball players that may skew the results. You determine to run a Kruskal-Wallis Test. How would you state the null-hypothesis?

Null Hypothesis for a Kruskal Wallis Test

Null Hypothesis for a Kruskal Wallis TestThere is no statistically significant difference between the Median slices of pizza eaten byby football, basketball, and soccer players.

It’s time to practice:

Read the problem that follows and verbalize in your mind what the null-hypothesis would be

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) was compared.

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) was compared.

Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product").

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) was compared.

Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product").

1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final 1/3 of the participants gave ratings for Brand Z.

Here is the data set:

Brand "X" Brand "Y" Brand "Z"

Participant Rating Participant Rating Participant Rating

1 3 7 1 13 10

2 4 8 2 14 9

3 2 9 1 15 9

4 6 10 1 16 10

5 2 11 3 17 8

6 5 12 2 18 10

Template

There is no statistically significant difference between the median [insert dependent variable] by [insert first level of the independent variable], [insert second level of the independent variable], and [insert third level of the independent variable].

How would you state the null-hypothesis for this problem using this particular template?

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median [insert dependent variable] by [insert first level of the independent variable], [insert second level of the independent variable], and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median [insert dependent variable] by [insert first level of the independent variable], [insert second level of the independent variable], and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by [insert first level of the independent variable], [insert second level of the independent variable], and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by [insert first level of the independent variable], [insert second level of the independent variable], and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by Brand X, [insert second level of the independent variable], and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by Brand X, Brand Y, and [insert third level of the independent variable].

The effectiveness of advertising for three products (Brand X, Brand Y, and Brand Z) were compared. Market research at a local shopping center was carried out, with the participants being shown advertisements for three brands of soda, which they then rated on the overall likelihood that they would buy the product (out of 10, with 10 being "definitely going to buy the product"). 1/3 of the participants gave ratings for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by Brand X, Brand Y, and Brand Z.

for Brand X , 1/3 gave ratings for Brand Y , and a final third of the participants gave ratings for Brand Z.

There is no statistically significant difference between the median likelihood to buy the product by Brand X, Brand Y, and Brand Z.