![]() Numerous high-quality statistical packages are available in Edinburgh good ones include MINITAB and Splus. Much better, however, are statistical packages that have been specially written to be 'user friendly' and to include a comprehensive suite of up-to-date statistical methods. Spreadsheets such as EXCEL contain a number of statistical functions, and these can be very helpful. The recent advent of spreadsheets and statistical/graphical software packages has transformed elementary statistical analysis from a rather mathematical subject, backed up by dense statistical tables, into a readily accessible technique. Analysis is the step between obtaining data and applying it to solve practical problems. Data analysis includes (i) organising measurements into a meaningful order or into groups, (ii) reducing the data into manageable quantities, (iii) forming succinct descriptions of the main features of the data, and (iv) elucidating any anomalies for subsequent examination. ![]() Measurements are of little use until they are 'analysed'. (Roy Thompson, Geology & Geophysics Department) Practical statistical analyses using MINITAB The command Stat>Regression>Fitted line plot will produce the same output in the session window plus a scatterplot with the rgression line graphed on it.Practical statistical analyses using Minitab ![]() The result gives the regression equation and the coefficient of determination (r-squared - labeled "R-sq") and further information - notably pairs with large residuals (potential outliers) and values whose x-values are ver different (influential points) - used for analysis of the equation. ![]() For the "response" select the variable to be the "y" variable (predicted by the eauation) and for the "predictor" use your "x" variable (used to predict the response). Regression line and coefficient of determination (r-square): Use Stat>Regression>Regression. If you select more than two variables, you will geat a table giving the correlations between all pairs of variables. Select the variables for which you want the correlation. Listing the data in the session window is accomplished with the File>Display data command (select the column or columns you want displayed) - useful if you want a complete list of the values of one variable without printing the whole data window.Ĭorrelation coefficient (Pearson's r): Use Stat>Basic Statistics>Correlation. The row with the median is marked in parentheses.This is really a character graph - it shows up in the Session window - it's on the main graph menu because people use it a lot. In the display, an extra column at the left of the display shows the "depth" of the class - the distance (number of items) from the nearer end (large or small) of the data. You can set the increment at 5 to get a split stemplot. Select the variable(s) by double-clicking in the list at the left of the window. The resulting printout shows class midpoints (no class limits) and frequencies. The Interval is the class width (class interval, range for the class), the First midpoint is the class midpoint of the first class. Select the variable(s) by double-clicking in the list. Grouped frequency distribution : Use Graph>Character Graphs>Histogram. Q3 the third quartile - value separating the smallest three-quarters of the values from the rest Other descriptions Q1 the first quartile - value separating the smallest quarter of the values from the rest SEMean the standard error of the mean - the standard deviation divided by the square root of N StDev the standard deviation (s) of the values TrMean the 5% trimmed mean - the mean with the largest 5% and smallest 5% of the values deleted Mean the arithmetic mean (x-bar) of the values Median the "middle" value (half the values are at or above, half are at or below) Variable the name of the variable (unless you didn't name it - then you get the column number) With the cursor in the "Variables" box, select the columns you want described (highlight them and click on " Select " - or simply double-click on them) and click on OK (or press the Return/Enter key). Some descriptive statistics A: One-variable description Most complete description (pretty much all the one-variabledescription you need)įor the most commonly used descriptive measures, select Stat>Basic Statistics>Descriptive statistics. Minitab: Descriptive Statistics Introduction to MINITAB in the Saint Mary's MicrocomputerLab V.
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