Originally posted by Toledo Inquisition
View Post
Announcement
Collapse
No announcement yet.
Ty Cobb discussion
Collapse
X

Originally posted by AstrosFan View PostRe: Correlation between BB rate and Iso
I ran the numbers for 190318 and for 191935, which gave me two samples of about equal size: 5,318 and 5,202.
I calculated BB rate as BB/AB, which is what I usually see, though I have posted a question on that stat's calculation in the sabermetrics forum.
I used the CORREL function in Excel to make these calculations.
The correlation (r) for the deadball era was about .006. For the lively era, it was about .049.
The test statistic is calculated as r/sqrt((1r^2)/(n2)), where n is the sample size. N2 represents the degrees of freedom in calculating the test statistic for correlation.
Since I am making no assumption on whether the data is positively or negatively correlated before making the calculations, I am using the twotailed alternative hypothesis. The null hypothesis is simply that the two are not related.
The critical value for a twotailed alternative is +/ 3.182
The test statistic for the deadball era is about .418. For the lively era, it is about 3.55.
Given that information, we would fail to reject the null for the deadball era, and reject it for the lively era. That suggests there was not a relationship between walk rate and iso in the deadball era, and there was one during the first 17 years of the live ball era.
Comment
Ad Widget
Collapse
Comment