EMPIRE™ Turf Research
Statistical significance in mowing rates difference
The following tests show the statistical significance in the difference in the mowing rates, and have been derived from a market research program.
The purpose of the research was to test the theory that there were differences in the mowing rates for Kikuyu & Couch compared to Empire Turf.
The following tests prove that there is a significant difference in mowing rates for the three different varieties.
- TEST 1
Kikuyu compared to EMPIRE™ Turf - fertilised twice per year - TEST 2
Couch compared to EMPIRE™ Turf - fertilised twice per year - TEST 3
Kikuyu compared to EMPIRE™ Turf - fertilised once per year - TEST 4
Couch compared to EMPIRE™ Turf - fertilised once per year - TEST 5
Kikuyu compared to EMPIRE™ Turf - under moderate wearing conditions
The purpose of a means test is to compare the size of the difference between two means in relation to the amount of inherent variability (the random error) in the data. If the random error is large then we are unlikely to find a significant difference between means unless this difference is also very large.
The paired T tests use standard deviation and the mean (or average) for the mowing rates to compare the difference in mowing.
TEST 1
Kikuyu compared to EMPIRE™ Turf - fertilised twice per year
To test whether there was a difference in the mowing rate of EMPIRE™ and Kikuyu when fertilised twice per year, the following paired samples test was conducted.
Ho: µ diff = 0 or in other words no difference
H1: µ diff > 0 or < 0 or is there a significant difference
Reject Ho if sig value < 0.05
Since 0.03 < 0.05 we reject Ho and conclude there is a significant difference in the mean mowing rates for EMPIRE™ and Kikuyu, at the 95% confidence level.
| Paired Samples Statistics | |||||
| Mean | No. | Std. Deviation | Std. Error Mean | ||
| Pair 1 | EMPIRE2 | 21.2333 | 30 | 6.5637 | 1.1984 |
| KIKUYU2 | 48.9333 | 30 | 7.5014 | 1.3696 | |
| Paired Samples Correlations | ||||
| No. | Correlation | Sig | ||
| Pair 1 | EMPIRE2 & KIKUYU2 |
30 | 0.528 | 0.003 |
| Paired Samples Test | |||||
| Paired Differences | |||||
| Mean | Std. Deviation | Std. Error Mean | 95% Confidence Interval of the Difference | ||
| Lower | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-27.7000 | 6.8840 | 1.2568 | -30.2705 |
| Sig. (2-tailed) | |||||
| t | d | ||||
| Upper | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-25.1295 | -22.039 | 29 | 0.000 |
Conclusion: There is a significant difference between the mowing rates, thus with EMPIRE™ Turf you can save yourself a lot of money and time by not having to mow your lawn as regularly.
TEST 2
Couch compared to EMPIRE™ Turf - fertilised twice per year
To test whether there was a significant difference in the mean mowing rates for EMPIRE™ and Couch grass when fertilised twice per year, the following paired samples test was conducted.
Ho: µ diff= 0 or in other words no difference
H1: µ diff > 0 or < 0 or is there a significant differenceReject Ho if sig value < 0.05
Since 0.256 < 0.05 we accept Ho and conclude there is no significant difference
in the mean mowing rates for EMPIRE™ and Couch.
| Paired Samples Statistics | |||||
| Mean | No. | Std. Deviation | Std. Error Mean | ||
| Pair 1 | EMPIRE2 | 21.2333 | 30 | 6.5637 | 1.1984 |
| COUCH2 | 37.8667 | 30 | 7.9989 | 1.4604 | |
| Paired Samples Correlations | ||||
| No. | Correlation | Sig | ||
| Pair 1 | EMPIRE2 & COUCH2 |
30 | 0.214 | 0.256 |
| Paired Samples Test | |||||
| Paired Differences | |||||
| Mean | Std. Deviation | Std. Error Mean | 95% Confidence Interval of the Difference | ||
| Lower | |||||
| Pair 1 | EMPIRE2 & COUCH2 |
-16.6333 | 9.1970 | 1.6791 | -20.0676 |
| Sig. (2-tailed) | |||||
| t | d | ||||
| Upper | |||||
| Pair 1 | EMPIRE2 & COUCH2 |
-13.1991 | -9.908 | 29 | 0.000 |
Conclusion: There is no significant difference in the mowing rates of Couch and EMPIRE™ at the 95% confidence level.
TEST 3
Kikuyu compared to EMPIRE™ Turf - fertilised once per year
One of our aims was to research the difference in mowing rates for EMPIRE™ compared to other grasses when only fertilised once per year. The reason for this is that EMPIRE™ Turf has a distinct advantage as it will still look great even if it is only fertilised once per year, whilst other grasses may thin out. The mowing rates of turf when fertilised only once per year was also of interest.
To test whether there was a difference in the mowing rate of EMPIRE™ and Kikuyu when fertilised once per year, the following paired samples test was conducted.
Ho: µ diff= 0 or in other words no difference
H1: µ diff > 0 or < 0 or is there a significant differenceReject Ho if sig value < 0.05
Since 0.04 < 0.05 we reject Ho and conclude there is a significant difference in the mean mowing rates for EMPIRE™ and Kikuyu, when fertilised once per year.
| Paired Samples Statistics | |||||
| Mean | No. | Std. Deviation | Std. Error Mean | ||
| Pair 1 | EMPIRE2 | 16.7000 | 30 | 5.7304 | 1.0462 |
| KIKUYU2 | 39.5000 | 30 | 7.8466 | 1.4326 | |
| Paired Samples Correlations | ||||
| No. | Correlation | Sig | ||
| Pair 1 | EMPIRE2 & KIKUYU2 |
30 | 0.507 | 0.004 |
| Paired Samples Test | |||||
| Paired Differences | |||||
| Mean | Std. Deviation | Std. Error Mean | 95% Confidence Interval of the Difference | ||
| Lower | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-22.8000 | 6.9847 | 1.2752 | -25.4081 |
| Sig. (2-tailed) | |||||
| t | d | ||||
| Upper | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-20.1919 | -17.879 | 29 | 0.000 |
Conclusion: Since 0.04 < 0.05 we reject Ho and conclude there is a significant difference in the mean mowing rates for EMPIRE™ and Kikuyu, when fertilised once per year.
TEST 4
Couch compared to EMPIRE™ Turf - fertilised once per year
To test whether there was
a significant difference in the mean mowing rates for EMPIRE™ Turf and Couch when fertilised once per year, the following
paired samples test was conducted.
Ho: µ diff= 0 or in other words no difference
H1: µ diff > 0 or < 0 or is there a significant differenceReject Ho if sig value < 0.05
Since 0.381 < 0.05 we accept Ho and conclude there is no significant difference in the mean mowing rates for EMPIRE™ and Couch.
| Paired Samples Statistics | |||||
| Mean | No. | Std. Deviation | Std. Error Mean | ||
| Pair 1 | EMPIRE2 | 16.7000 | 30 | 5.7304 | 1.0462 |
| COUCH2 | 31.9000 | 30 | 8.4582 | 1.5443 | |
| Paired Samples Correlations | ||||
| No. | Correlation | Sig | ||
| Pair 1 | EMPIRE2 & COUCH2 |
30 | 0.166 | 0.381 |
| Paired Samples Test | |||||
| Paired Differences | |||||
| Mean | Std. Deviation | Std. Error Mean | 95% Confidence Interval of the Difference | ||
| Lower | |||||
| Pair 1 | EMPIRE2 & COUCH2 |
-15.2000 | 9.3970 | 1.7156 | -18.7089 |
| Sig. (2-tailed) | |||||
| t | d | ||||
| Upper | |||||
| Pair 1 | EMPIRE2 & COUCH2 |
-11.6911 | -8.860 | 29 | 0.000 |
Conclusion: There is no significant difference at the 95% confidence interval for EMPIRE™ Turf and Couch.
TEST 5
Kikuyu compared to EMPIRE™ Turf - under moderate wearing conditions
The final test that we wanted was to compare EMPIRE™ Turf to Kikuyu under moderate wearing conditions. It is recommended that Kikuyu needs fertilizing twice per year, whilst EMPIRE™ only requires fertilising once per year. Part of this included comparing the mowing rates in moderate wearing areas.
Ho: µ diff= 0 or in other words no difference
H1: µ diff > 0 or < 0 or is there a significant differenceReject Ho if sig value < 0.05
Since 0.000 < 0.05 we reject Ho and conclude that there
is a significant deifference in the mowing rates of EMPIRE™ Turf and Kikuyu.
| Paired Samples Statistics | |||||
| Mean | No. | Std. Deviation | Std. Error Mean | ||
| Pair 1 | EMPIRE2 | 16.7000 | 30 | 5.7304 | 1.0462 |
| KIKUYU2 | 48.9333 | 30 | 7.5014 | 1.3696 | |
| Paired Samples Correlations | ||||
| No. | Correlation | Sig | ||
| Pair 1 | EMPIRE2 & KIKUYU2 |
30 | 0.767 | 0.000 |
| Paired Samples Test | |||||
| Paired Differences | |||||
| Mean | Std. Deviation | Std. Error Mean | 95% Confidence Interval of the Difference | ||
| Lower | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-32.2333 | 4.8115 | 0.8785 | -30.4367 |
| Sig. (2-tailed) | |||||
| t | d | ||||
| Upper | |||||
| Pair 1 | EMPIRE2 & KIKUYU2 |
-34.0300 | 36.693 | 29 | 0.000 |
Conclusion: There is a significant difference in the mowing rates of EMPIRE™ Turf compared to Kikuyu under moderate wearing conditions. Thus if you want to save yourself time and money purchase some EMPIRE™ turf and enjoy the difference.