Question

A dentist wants to find the average time taken by one of her hygienists to take X-ray and clean the tooth for her patients. She recorded the time to serve 24 randomly selected patients by the hygienist. The data of this experiment are save in the column “Time” of the SPSS file .

	Time
	36.80 39.80 38.60 38.30 35.80 32.60 38.70 34.50 37.00 32.00 40.90 33.80 37.10 31.00 35.10 38.20 36.60 38.80 39.60 39.70 35.10 38.20 32.70 40.50

1. Compute the appropriate point estimate for population (true) mean time taken by this hygienist.

2. Construct a 98% confidence interval for the true average time taken by this hygienist.

3. The standard average for all the hygienists for this type of job is 34 minutes. Do the sample data provides evidence that the average time taken by the hygienist is longer than standard average for this job type? Use 1% significance level.                 

Please write how could I do it in SPSS

Answer 1

Ans- a)

SPSS output for the data is

Descriptive Statistics
	N	Minimum	Maximum	Mean	Std. Deviation
Time	24	31.00	40.90	36.7250	2.83614
Valid N (listwise)	24

point estimate of mean is 36.72

steps in SPSS- put the data in SPSS and select the scale variable .now you go through with

Analyze> Discriptive statistic> Discriptive > OPTION> tick on mean

and then continue .

Ans(b)- 98% confidence interval for the true average time taken by this hygienist = (-1.4422,1.4522)

One-Sample Test
	Test Value = 36.72
	t	df	Sig. (2-tailed)	Mean Difference	98% Confidence Interval of the Difference
					Lower	Upper
Time	.009	23	.993	.00500	-1.4422	1.4522

Steps-

Ans(C)- assume the hypothesis

H₀ - standard average for all the hygienists for this type of job is 34 minutes i.e

H1 - standard average for all the hygienists for this type of job is longer then 34 minutes i.e  

One-Sample Test
	Test Value = 34
	t	df	Sig. (2-tailed)	Mean Difference	99% Confidence Interval of the Difference
					Lower	Upper
Time	4.707	23	.000	2.72500	1.0998	4.3502

Interpretation - Here p- value is 0.000<0.01 that mean there is strong evidence against the Nulll hypothesis hence we reject the null hypothesis.since standard average for all the hygienists for this type of job is longer than standard average for this job type.

steps in SPSS-