Confidence interval: what it means and how to read it
In the report: Confidence interval — The confidence interval of the estimate: its level and its two bounds.
In plain words
A shop owner looked at 60 orders and found that the average order was 40 dollars. But she did not know whether the average of all her orders, past and future, is really 40. The confidence interval section gave her the level, 95 percent, and two bounds, 36 and 44. Now she can say that the usual order over all her customers is probably somewhere between 36 and 44 dollars. A plan that needs 50 dollars per order would be a stretch, and a plan that needs 38 looks safe.
Example
The cell with Confidence interval is selected in each report; point at a label to see its note.
- — the sample data (50 rows) the examples use
- —
=STATS_SPEARMAN(Data!A1:T51, "x,y",0.95,"two-sided") - — x1 and x2 with age held constant
=STATS_PARTIAL(Data!A1:T51, "x1,x2", "age") - —
=STATS_PAIRED(Data!A1:T51, "before,after",0.95,"two-sided")
Where you see it
STATS_PEARSON— Pearson correlation (r).STATS_SPEARMAN— Spearman rank correlation (rho): the correlation for rating scales, ranks and skewed data — does one go up as the other goes up?STATS_KENDALL— Kendall rank correlation (tau-b): the correlation of the order of two columns — for small samples and scales with many tied answers.STATS_PARTIAL— Partial correlation: the Pearson correlation of two variables with the controls held constant (SPSS PARTIAL CORR). Two variables give one correlation, three or more a matrix, as STATS_PEARSON.STATS_PAIRED— Paired-samples t-test for two related measurements (e.g., pre vs post).STATS_INDEPENDENT— Independent-samples t-test for two groups: the two selected columns are the groups.STATS_ONE_SAMPLE— One-sample t-test against mu0.STATS_ANALYZE— Runs several analyses on one range and returns one report.
Related values
- Confidence level — The confidence level of the interval: ciLevel, 0.95 by default.
- Significance of the partial correlation — The p of the partial correlation, as SPSS names it, for the chosen alternative. Empty in the same cases as Correlation.
- Alternative hypothesis — The hypothesis tested: two-sided — the means differ in either direction; greater — the first is larger; less — the first is smaller.
- Exact significance — The exact p of U (Dineen and Blakesley), shown only for small groups without ties, as SPSS; for a two-sided test twice the one-tailed p.
- Margin of error — Half the width of a two-sided interval: the t quantile times the standard error.
Get it in your sheet
One formula in a cell gives the whole report, Confidence interval included. ALS Stats is a free add-on for Google Sheets™.
Install ALS Stats from Google Workspace Marketplace (opens in a new tab)