I think the question is is it going back and forth from one day to the next, and then back again, or did it change once and that's it? If it is changing daily then I would guess there is something(s) very worn in the steering components such as tie rod ends, drag link, ball joints etc. I suppose it could be the steering gear/box also. If you want more specific info you need to state what car you are talking about.

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1998 C230 330,000 miles (currently dead of second failed EIS, yours will fail too, turning you into the dealer's personal human cash machine)
1988 F150 144,000 miles (leaks all the colors of the rainbow)
Previous stars: 1981 Brava 210,000 miles, 1978 128 150,000 miles, 1977 B200 Van 175,000 miles, 1972 Vega (great, if rusty, car), 1972 Celica, 1986.5 Supra