Home |
Search |
Today's Posts |
#1
Posted to microsoft.public.excel.charting
|
|||
|
|||
trend line equations
I have made a graph of some data in excel (temp vs. year) and added a linear
and quadratic trend line. When I take the equations from the trendlines and try to project into the future by pluggin in higher x values into the equation the quadratic values are incorrect. What I mean is that the values resulting from the trend line are not in the same y range as the original data from which the trendline was made. How can the same equation describe two different graphs? Here is the data: 1950 1.05 1951 2.2 1952 3.735 1953 4.03 1954 3.07 1955 3.605 1956 2.68 1957 2.7 1958 2.905 1959 2.705 1960 2.995 1961 3.575 1962 2.625 1963 2.72 1964 3.035 1965 2.185 1966 2.59 1967 2.115 1968 3.025 1969 2.975 1970 2.59 1971 2.66 1972 1.115 1973 3.685 1974 2.12 1975 3.12 1976 2.235 1977 3.195 1978 2.075 1979 1.705 1980 2.39 1981 3.545 1982 1.985 1983 3.55 1984 3.38 1985 2.215 1986 3.4 1987 5.115 1988 3.13 1989 2.04 1990 3.675 1991 3.615 1992 2.725 1993 2.515 1994 3.08 1995 3.105 1996 1.85 1997 3.05 1998 5.635 1999 4.705 2000 3.74 2001 4.8 2002 3.585 2003 3.095 2004 2.985 2005 4.26 Any help would be greatly appreciated since this is really frustrating me. The linear graph seems to make sense but the quadratic or cubic do not. Thanks, Katy |
Thread Tools | Search this Thread |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Forum | |||
How do I set a Trend Line and Remove the Data Line | Charts and Charting in Excel | |||
Timeseries Trend Equations--Units? | Excel Discussion (Misc queries) | |||
Idential trend line equations show different trends | Excel Discussion (Misc queries) | |||
Which trend line? | New Users to Excel | |||
Move equations from line to line automatically | Excel Discussion (Misc queries) |