The number of new US book titles increased from almost 47,000 in 1990 to over 48,000 in 1991. However, this was still below the historic high of about 56,000 titles attained in 1987 (Grannis, 1992). Can we expect an increase or decrease in price of books, especially hardbacks, if there are more competitors in the market? The following table gives the number of titles and the average price of hardback books classified according to 23 standard subject categories representing one or more specific Dewey Decimal Classification numbers.
See attached file for data.
Consider the number of volumes and average price per volume in 1990 and in 1991 as paired samples for two randomly selected years of 23 categories of books.
1. Determine whether the difference in the average number of volumes per category for 1991 differs significantly from the 1990 average.
2. Determine whether the change in the average price of a hardback book per category in 1991 differs significantly from that in the 1990 average.
3. Summarize your results concerning the difference in the number and price of books per category in 1991 compared with 1990.
Do the data provide sufficient evidence to indicate volume and price variability between 1990 and 1991? Also indicate whether the null hypothesis is rejected or not rejected, the type of error possibly made, and the conclusion or answer to the stated research question. Use the 8-step of hypothesis testing procedure to report the findings and include a copy of the computer printout.
This solution provides calculations in Excel for various questions for testing a hypothesis.