# case0602: Mate Preference of Platyfish In Sleuth3: Data Sets from Ramsey and Schafer's "Statistical Sleuth (3rd Ed)"

## Description

Do female Platyfish prefer male Platyfish with yellow swordtails? A.L. Basolo proposed and tested a selection model in which females have a pre-existing bias for a male trait even before the males possess it. Six pairs of males were surgically given artificial, plastic swordtails—one pair received a bright yellow sword, the other a transparent sword. Females were given the opportunity to engage in courtship activity with either of the males. Of the total time spent by each female engaged in courtship during a 20 minute observation period, the percentages of time spent with the yellow-sword male were recorded.

## Usage

 `1` ```case0602 ```

## Format

A data frame with 84 observations on the following 3 variables.

Percentage

The percentage of courtship time spent by 84 females with the yellow-sword males

Pair

Factor variable with 6 levels—`"Pair1"`, `"Pair2"`, `"Pair3"`, `"Pair4"`, `"Pair5"` and `"Pair6"`

Length

Body size of the males

## Source

Ramsey, F.L. and Schafer, D.W. (2013). The Statistical Sleuth: A Course in Methods of Data Analysis (3rd ed), Cengage Learning.

## References

Basolo, A.L. (1990). Female Preference Predates the Evolution of the Sword in Swordtail Fish, Science 250: 808–810.

## Examples

 ``` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40``` ```str(case0602) attach(case0602) ## EXPLORATION plot(Percentage ~ Length, xlab="Length of the Two Males", ylab="Percentage of Time Female Spent with Yellow-Sword Male", main="Percentage of Time Spent with Yellow Rather than Transparent Sword Male") abline(h=50) # Draw a horizontal line at 50% (i.e. the "no preference" line) myAov <- aov(Percentage ~ Pair) plot(myAov, which=1) # Resdiual plot summary(myAov) # Explore possibility of linear effect, as in Display 6.5 myAov2 <- aov(Percentage ~ Pair - 1) # Show the estimated means. myContrast <- rbind(c(5, -3, 1, 3, -9, 3)) if(require(multcomp)){ # Use the multcomp library myComparison <- glht(myAov2, linfct=myContrast) summary(myComparison, test=adjusted("none")) } # Simpler exploration of linear effect, via regression (Ch. 7) myLm <- lm(Percentage ~ Length) summary(myLm) # ONE-SAMPLE t-TEST THAT MEAN PERCENTAGE = 50%, IGNORING MALE PAIR EFFECT t.test(Percentage, mu=50, alternative="greater") # Get 1-sided p-value t.test(Percentage, alternative="two.sided") # Get C.I. ## SCATTERPLOT FOR PRESENTATION plot(Percentage ~ Length, xlab="Length of the Two Males (mm)", ylab="Percentage of Time Female Spent with Yellow-Sword Male", main="Female Preference for Yellow Rather than Transparent Sword Male", pch=21, lwd=2, bg="green", cex=1.5 ) abline(h=50,lty=2,col="blue",lwd=2) text(29.5,52,"50% (no preference)", col="blue") detach(case0602) ```

Sleuth3 documentation built on May 29, 2017, 11:28 a.m.