You are here: Lists & Spreadsheet Application > Confidence Intervals

## Confidence Intervals

### Supported Confidence Intervals

The following confidence intervals are available from the Lists & Spreadsheets application. For more information regarding these functions, see the TI‑Nspire™ Reference Guide.

#### z Interval (zInterval)

Computes a confidence interval for an unknown population mean, m, when the population standard deviation, s, is known. The computed confidence interval depends on the user-specified confidence level.

This test is useful in determining how far from a population mean a sample mean can get before indicating a significant deviation.

#### t Interval (tInterval)

Computes a confidence interval for an unknown population mean, m, when the population standard deviation, s, is unknown. The computed confidence interval depends on the user-specified confidence level.

This test is useful in examining whether the confidence interval associated with a confidence level contains the value assumed in the hypothesis. Like the z Interval, this test helps you determine how far from a population mean a sample mean can get before indicating a significant deviation when the population mean is unknown.

#### 2-Sample z Interval (zInterval_2Samp)

Computes a confidence interval for the difference between two population means (m1Nm2) when both population standard deviations (s1 and s2) are known. The computed confidence interval depends on the user-specified confidence level.

This test is useful in determining if there is statistical significance between the means of two samples from the same population. For example, this test could determine whether there is significance between the mean college entrance test score of female students and the mean of college entrance test score of male students at the same school.

#### 2-Sample t Interval (tInterval_2Samp)

Computes a confidence interval for the difference between two population means (m1Nm2) when both population standard deviations (s1 and s2) are unknown. The computed confidence interval depends on the user-specified confidence level.

This test is useful in determining if there is statistical significance between the means of two samples from the same population. It is used instead of the 2-sample z confidence interval in situations where the population is too large to measure to determine the standard deviation.

#### 1-Prop z Interval (zInterval_1Prop)

Computes a confidence interval for an unknown proportion of successes. It takes as input the count of successes in the sample x and the count of observations in the sample n. The computed confidence interval depends on the user-specified confidence level.

This test is useful in determining the probability of a given number of successes that can be expected for a given number of trials. For instance, casino examiners would use this test to determine if observed payouts for one slot machine demonstrate a consistent pay out rate.

#### 2-Prop z Interval (zInterval_2Prop)

Computes a confidence interval for the difference between the proportion of successes in two populations (p1-p2). It takes as input the count of successes in each sample (x1 and x2) and the count of observations in each sample (n1 and n2). The computed confidence interval depends on the user-specified confidence level.

This test is useful in determining if two rates of success differ because of something other than sampling error and standard deviation. For example, a bettor could use this test to determine if there is an advantage in the long run by playing one game or machine versus playing another game or machine.

#### Linear Reg t Intervals (LinRegtIntervals)

Computes a linear regression t confidence interval for the slope coefficient b. If the confidence interval contains 0, this is insufficient evidence to indicate that the data exhibits a linear relationship.

#### Multiple Reg Intervals (MultRegIntervals)

Computes multiple regression prediction confidence interval for the calculated y and a confidence for y.

© 2006 - 2016 Texas Instruments Incorporated