If no correlation exists between the variables, the points appear randomly scattered on the coordinate plane. If a large correlation exists, the points concentrate near a straight line. Scatter plots are useful data visualization tools for illustrating a trend. If the vertical (or y-axis) variable increases as the horizontal (or x-axis) variable increases, the correlation is positive.
Whiplash Whiplash, a severe neck injury, can cause stiffness and pain in the neck, headache, dizziness, and more. Aortic stenosis Aortic stenosis is a condition of the heart causing shortness of breath, dizziness, or chest pain.
Cervicogenic headaches are often accompanied with neck, mid, upper back or shoulder pain. Stiffness and soreness in the muscles of the neck, shoulders or upper back is also very common. You may find increased pain or tenderness in the neck at the same time the headache pain increases, often a reliable clue. A careful history may reveal previous trauma or injury, such as whiplash.