ONE-SAMPLE HYPOTHESIS TEST OF MEANS.

January 22, 2026

An image of the SPSS Histogram (Sample Data - Consumer Spending)
SPSS Histogram - A random sample of consumer spending.

Depending on the p-value, we reject or fail to reject the null hypothesis (H0). If p-value < the significance level, we reject H0.

Hypothesis testing compares a sample mean to the population mean—a theoretical, an existing level, a rate, or a standard—to reject the null hypothesis.

In the following example, the company wants to find out the evidence to support the claim that the average consumer spending < $380 in a typical month.

Example 12

A large retail company has a chain of stores. The chain store sales, given in the following table, represent a random sample of consumer spending in a typical month. Based on the hypothetical data given in the table, see if there is evidence that the average amount spent on groceries is less than $380. Use α= 0.05. Assume that the survey data collected by the store chain follow a normal distribution.

Case Store ID Customer ID Amount Spent ($)
1 1 2 383
2 2 21 341
3 8 142 265
4 9 162 359
5 15 285 537
6 17 323 311
7 19 364 511
8 21 402 225
9 21 403 379
10 25 485 227
11 25 487 386
12 25 488 358
13 26 501 253
14 26 504 555
15 27 521 322
16 27 522 530
17 32 622 412
18 36 702 382
19 37 729 366
20 38 742 345
21 39 762 292
22 42 821 487
23 43 846 579
24 53 1044 403
25 54 1061 343
26 54 1062 289
27 54 1066 367
28 56 1106 202
29 59 1161 386

When we selected an α = 0.05 (or 95% confidence), we are accepting a 5% chance of being wrong (type I error).

Create the variables (StoreID, CustID, and Amount) directly in the variable view, and input the sample data into the data view.


Name Type Values Missing Measure
1 StoreID Numeric None None Nominal
2 CustID Numeric None None Nominal
3 Amount Numeric None None Scale
  • H0: The NULL hypothesis (States “No difference”)
  • H1: The ALTERNATIVE (or research) hypothesis (States “There is a difference”)

TWO-TAILED TEST

  • H0: µ = $380 Mean monthly grocery spending per consumer
  • H1: µ ≠ $380 Mean monthly grocery spending per consumer

Run One-Sample T test…

Analyze → Compare Means → One-Sample T Test…

An image of the SPSS One-Sample T Test Inputs.
SPSS One-Sample T Test Inputs.
  • Move the variable (Amount) into the “Test Variable(s)” box
  • Options: Change Confidence Interval percentage (95%, 99% ..)—CI
  • Input the value (380) into the “Test Value” box
  • Run the test (OK)
  • Output: “Sig. (2-tailed)” is the P-value for two-sided test

The p value (0.681) is greater than 5% so we fail to reject the null hypothesis.

An image of the SPSS One-Sample T Test Output
SPSS One-Sample T Test Output.

ONE-TAILED TEST

  • H0: µ = $380 Mean monthly grocery spending per consumer
  • H1: µ < $380 Mean monthly grocery spending per consumer

Run One-Sample T test…

Analyze → Compare Means → One-Sample T Test…

  • Move the variable (Amount) into the “Test Variable(s)” box
  • Options: Change Confidence Interval percentage (95%, 99% ..)—CI
  • Input the value (380) into the “Test Value” box
  • Run the test (OK)
  • Output: “Sig. (2-tailed)” is the P-value for two-sided test.

The one-sided T Test, p-value should be (Sig. 2-tailed)/2. Therefore, one-sided T Test, p-value (0.3405) is greater than 5%. So, we also fail to reject the null hypothesis with one-sided T Test.

 

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