Correlation and Significance - Is this approach correct? Hello, Could any one please confirm the following; I have two columns of data (temperature) that I would like to compare. I would like to understand the statistical relationship between the two. I have about 1200 temperature measurements. Is the following approach valid? Find the correlation coefficient: ‘r’ I then find the coefficient of determination: ‘r2’ I then find the t value to test significance of a correlation coefficient using this formula:
t = r * SQRT((n-2)/(1-r^2)) If the value of t is less than the critical value, which is found from a table corresponding to the desired significance level, then the null hypothesis cannot be rejected i.e. there is no relationship. If it’s greater then that level of significance is achieved. When I use my figures I get a r value of 0.73 and so r^2 = 0.53 When I use n = 1200 it gives a t-value = 36.85 When I look up critical values for two tailed significance the 0.0001 significance level is 3.91 for n = 1000 (this was the largest value for n given). My questions are: Is this approach correct? Because 36.85>>3.91 does this mean that indeed there is a very strong positive correlation and also has a very high level of significance?? Does it matter which table of critical values I use i.e. single or two-tailed critical values? Any help would be greatly appreciated. Thanks. |